首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1361篇
  免费   50篇
  国内免费   9篇
耳鼻咽喉   44篇
儿科学   91篇
妇产科学   106篇
基础医学   101篇
口腔科学   49篇
临床医学   91篇
内科学   268篇
皮肤病学   51篇
神经病学   95篇
特种医学   39篇
外科学   279篇
综合类   15篇
预防医学   25篇
眼科学   71篇
药学   66篇
中国医学   1篇
肿瘤学   28篇
  2023年   1篇
  2022年   10篇
  2021年   22篇
  2020年   15篇
  2019年   19篇
  2018年   36篇
  2017年   18篇
  2016年   38篇
  2015年   53篇
  2014年   42篇
  2013年   62篇
  2012年   81篇
  2011年   81篇
  2010年   58篇
  2009年   62篇
  2008年   112篇
  2007年   112篇
  2006年   126篇
  2005年   107篇
  2004年   125篇
  2003年   100篇
  2002年   86篇
  2001年   7篇
  2000年   1篇
  1999年   5篇
  1998年   1篇
  1997年   4篇
  1996年   2篇
  1995年   2篇
  1994年   3篇
  1993年   3篇
  1992年   4篇
  1991年   3篇
  1990年   1篇
  1989年   2篇
  1988年   3篇
  1987年   1篇
  1986年   2篇
  1985年   4篇
  1984年   5篇
  1979年   1篇
排序方式: 共有1420条查询结果,搜索用时 31 毫秒
1.
Low molecular weight heparins are widely used in the prophylaxis and treatment of thrombotic disorders. The effect of low molecular weight heparins on coagulation was examined ultrastructurally in an animal model. A test and a control group was formed, each consisting of five rabbits. Nadroparine (225 Institute of Chaoy Unit/kg twice daily) was applied to the test group for 10 days. The control group received 1 ml saline solution subcutaneously. Blood and vascular tissue samples collected at the end of the 10th day were evaluated under a JEM 100 B electron microscope. Platelet degranulation and agglutination was observed in the control group. Fibrin materials were detected in the cytoplasms and surroundings of degranulated platelets. Erythrocyte accumulation was remarkable on the vascular endothelium with intact coagulation periods. In the test group, outer membranes of platelets, hyalomere, and granular structures in the granulomeres were detected to be nearly intact. There were rare erythrocytes in the large vascular lumens. The aggregation phase had occurred but no agglutination was detected. Nadroparine seems to preserve consistency of lipoprotein membranes of platelets and granular structures containing enzymes, which contribute to the coagulation mechanisms.  相似文献   
2.
Ligneous periodontitis (LP) is a rare periodontal disease in which plasminogen deficiency and fibrin deposition both play a part, resulting in characteristic gingival enlargement and periodontal breakdown. Recent data suggest that oxidant/antioxidant changes are significant in the pathology of oral diseases. This study examines the gingival histopathology in 2 cases with LP. To examine the antioxidant (AO) status, the activity of the major AOs glutathione (GSH), catalase (CAT), and glutathione S-transferase (GST) and the malondialdehyde (MDA) levels, a product of lipid peroxidation, were measured and compared with healthy control subjects. The histopathologic examination of the gingiva revealed subepithelial fibrin accumulation and irregular extensive downward proliferation of the epithelium. Biochemical analysis showed that the CAT, GST, and MDA levels were higher in LP patients than in the control subjects, and the GSH level was lower. Our preliminary findings show that in LP, the AO capacity of the gingiva changes or decreases and lipid peroxidation increases, which suggests that oxidative stress is involved in the pathology of the periodontal breakdown observed in this disease.  相似文献   
3.
The effects of the anti-epileptic drugs valproic acid and gamma-vinyl-GABA j(vigabatrin) on the extracellular content of GABA was determined by microdialysis. Probes were implanted in the substantia nigra reticulata (SNR) of rats. It was found that gamma-vinyl-GABA (1000 mg/kg) induced a 4–6-fold increase in the extracellular content of GABA. This increase lasted for at least 72 h. PTZ-induced convulsions were partly antagonized by the GVG treatment. The increase of extracellular GABA after gamma-vinyl-GABA was not affected by infusion of tetrodotoxin. In contrast valproic acid (200 mg/kg), although effective in preventing pentylenetetrazol (PTZ)-induced convulsions, did not affect extracellular GABA in the SNR. PTZ-induced convulsions did not modify extracellular GABA, neither in control rats nor in valproic acid or gamma-vinyl-GABA pretreated animals. The results do not support the idea that extracellular GABA in the SNR plays a significant role in anti-convulsive treatment. However, the present data can also be interpreted that extracellular GABA, as sampled by microdialysis, is not a reliable marker for GABA release.  相似文献   
4.
Retroperitoneal cystic lymphangioma is a rare congenital malformation. The majority of lymphangiomas are present at birth and nearly all present before the age of two years. We report a case of giant cystic retroperitoneal lymphangioma in a patient who first presented with symptoms at the age of 7, underwent surgery, and who then suffered a recurrent mass 11 years later.  相似文献   
5.
Inhibition of chemokines prevents intraperitoneal adhesions in mice   总被引:2,自引:0,他引:2  
BACKGROUND: The present study evaluates the efficacy of a broad-spectrumchemokine inhibitor, NR58-3.14.3, in the prevention of adhesionformation after i.p. surgery in mice. METHODS: A total of 110eight week old female Balb/c mice underwent laparotomy. Fortyanimals were randomly assigned to receive daily i.p. injectionsof either vehicle (control) or NR58-3.14.3. Time-course of adhesionformation was assessed. A titration of NR58-3.14.3 was conductedfor i.p. and s.c. administrations. The effectiveness of a singleintra-operative dose of NR58-3.14.3 was evaluated. Number, extent,location and type of adhesions were recorded. Immunohistochemistryof adhesions was done with leukocyte common antigen, CD45. RESULTS:Adhesion scores peaked on post-operative days 6–8. Onboth days 6 and 8, there were smaller adhesion size and lowercumulative adhesion scores in NR58-3.14.3-treated group. Moreover,on day 8, there were significantly fewer adhesions in NR58-3.14.3-treatedgroup compared to controls. The least effective dose for i.p.administration of NR58-3.14.3 was 0.45 mg/animal. Subcutaneousand single intra-operative i.p. administrations were also effectivein the prevention of i.p. adhesions. Although NR58-3.14.3 decreasedthe number of CD45+ inflammatory cells in the adhesions by 22.5%compared to control group, this was not significant. CONCLUSIONS:Our results show that this broad-spectrum chemokine inhibitorprevents post-operative adhesions in mice and may have a potentialclinical use.  相似文献   
6.
BACKGROUND: The presence of hydrosalpinges is associated with lower implantation and pregnancy rates in women undergoing IVF-embryo transfer, while salpingectomy improves these parameters. Although the mechanism by which hydrosalpinges affects fertility is not entirely understood, an adverse effect on endometrial receptivity has been postulated. In this study, we hypothesized that the adverse effects of hydrosalpinges on fertility may be in part mediated by inappropriate endometrial expression of leukaemia inhibitory factor (LIF), a cytokine implicated in implantation. METHODS: In order to test our hypothesis, we prospectively examined the expression of LIF during the window of implantation in the endometrium of infertile women (n = 10) with hydrosalpinges prior to and following salpingectomy and of fertile controls (n = 10) by Western blotting and immunohistochemistry. RESULTS: LIF expression was significantly lower in infertile women with hydrosalpinges compared with fertile controls (P < 0.05). Salpingectomy resulted in an increase in LIF expression in eight out of 10 women with hydrosalpinges. LIF levels were increased by 231 +/-49% (mean +/- SEM) following salpingectomy. Immunohistochemical analysis confirmed the Western blot findings. The increased LIF immunoreactivity was predominantly localized to luminal and glandular epithelial cells. CONCLUSIONS: Our findings suggest that observed benefit from salpingectomy in infertile women with hydrosalpinges may be in part mediated by the up-regulation of endometrial LIF expression.  相似文献   
7.
BACKGROUND: Patients with exercise-induced bronchospasm (EIB) may benefit from a prophylactic beta2-adrenergic agonist that combines rapid onset with long duration of action. OBJECTIVE: To compare the protective effect against EIB of a single inhaled dose of formoterol powder delivered via the Aerolizer inhaler (Novartis Pharmaceuticals, East Hanover, NJ) with the effect of placebo and albuterol. METHODS: Eighteen patients with EIB were randomized to treatment in a double-blind, placebo-controlled, four-way, crossover study. Seventeen patients completed all four crossover periods. Each patient received in random sequence a single dose of formoterol (12 or 24 microg), albuterol (180 microg), or placebo at intervals of 5 +/- 2 days. Pulmonary function measurements were taken before and after exercise challenge tests (ECTs) at 15 minutes postdosing and at 4, 8, and 12 hours postdosing. RESULTS: Both doses of formoterol produced significantly greater protection against EIB, compared with placebo, at all timepoints (P < or = 0.016). The two doses of formoterol were not significantly different from one another at any time. Protection against EIB with albuterol was clinically significant only for the 15-minute ECT and was statistically superior to placebo for the 15-minute and 4-hour ECTs. Although formoterol and albuterol exhibited a rapid onset of action, formoterol provided longer-lasting protection over the 12-hour observation period. Rescue medication was used substantially less with either dose of formoterol, compared with albuterol or placebo. All treatments were well tolerated. Two-hour postdosing electrocardiograms and vital signs were unremarkable for all study treatments. CONCLUSION: A single dose of formoterol (12 or 24 microg) provides protection against EIB within 15 minutes of dosing and persists for up to 12 hours. Formoterol is safe and well tolerated.  相似文献   
8.
In the present study, we tried to determine whether IUD insertion related PID and febrile complications could, be prevented by prophylactic use of antibiotics. We studied 300 patients who were admitted to our family planning clinic for IUD contraception. Of these, 150 patients received prophylactic Doxycycline (group 1) and the second 150 received no therapy (group 2). Five cases experienced fever with or without leucocytosis and none required hospitalization. PID was observed in one woman in each group.Positive culture (gonorrhea) was obtained in one woman who was then treated by relevant, antibiotics; the other woman required hospitalization for two days. The overall infection rates for group 1 and 2 were 2.1% and 2.9%, respectively and this difference was not significant. The incidence of PID infection and febrile complications was found to be very low for both groups when compared to other studies, suggesting that aseptic conditions with proper insertion reduce the risk of infection.
Resumen En el presente estudio, intentamos determinar si la inflamación pélvica y las complicationes febriles relacionadas con la inserción, de DIU podían evitarse mediante la administración profiláctica de antibióticos. Estudiamos a 300 pacientes de nuestra clínica de planificación familiar que recibieron DIU. Se administró un tratamiento profiláctico de doxicilina a 150 pacientes (Grupo 1) mientras que las restantes no recibieron ningún tratamiento (Grupo 2). Hubo cinco casos de fiebre con o sin leucocitosis pero ninguno requirió hospitalización. La inflamación pélvica se observó en dos casos, uno de cada grupo. Se obtuvo un cultivo positivo (gonorrea) en uno de los casos, que fue tratado con antibióticos apropiados, y el segundo caso debió ser hospitalizado durante dos días. Las tasas generales de infección fueron para el Grupo 1 y el Grupo 2, respectivamente, del 2,1% y del 2,9%, diferencia que no es significativa. Una comparación con otros estudios permitió verificar que la incidencia de infección pélvica inflamatoria y complicaciones febriles era muy baja en los dos grupos, lo cual hace pensar que las condiciones de asepsia y la inserción correcta reducen el riesgo de infección.

Resumé Dans la présente étude, nous avons tenté de déterminer si l'inflammation pelvienne et les complications fébriles liées à l'insertion de DIU pouvaient être évitées par une administration prophylactique d'antibiotiques. Nous avons suivi 300 patientes de notre clinique de planning familial, admises pour l'insertion, de DIU. Un traitement prophylactique de doxycycline a été administré à 150 de ces patientes (Groupe 1) et les autres n'ont reçu aucune, thérapie (Groupe 2). Nous avons eu cinq cas de fièvre avec ou sans leucocytose mais aucune de ces femmes n'a d être hospitalisée. L'inflammation pelvienne s'est manifestée dans deux cas, un dans chaque groupe. Une culture positive (gonorrhée) a été obtenue chez une de ces patientes, à laquelle un traitement aux antibiotiques appropriés a été administré, et la seconde a d être hospitalisée pendant deux jours. Les taux globaux d'infection ont été, respectivement pour le groupe 1 et le groupe 2, de 2,1% et 2,9%, ce qui ne représente pas une différence significative. Une comparaison avec d'autres études a permis, de constater que l'incidence d'infection pelvienne inflammatoire et de complications fébriles était très faible dans les deux groupes, ce qui laisse penser que les conditions d'asepsie et une insertion correcte réduisent le risque d'infection.
  相似文献   
9.
The reductive etherification reaction (RER) of carbonyl groups (aldehydes or ketones) through silane as a reducing agent together with Bronsted or Lewis acid affords the synthesis of symmetrical and unsymmetrical ethers. This strategy is applied at the macromolecular level for the first time in 1993, and isophthalaldehyde is self-polymerized in the presence of triethylsilane (Et3SiH)/ tritylperchlorate (TrClO4) to yield polyethers with low to moderate molecular weights. Next, the polyethers with alternating structures are achieved by reacting isophthalaldehyde with bis(trimethylsilyl) ethers or diols as comonomers using reducing agent silane and Lewis acid. Moreover, in recent years, it is shown that polyether synthesis and post-polymerization modification (PPM) of polymers proceeds smoothly and effectively with the RER strategy in the presence of chlorodimethylsilane (CDMS), which acts as both a reducing agent and a Lewis acid.  相似文献   
10.
In hypersensitive reactions to native L‐asparaginase, either premedication and desensitization or substitution with polyethylene glycol conjugated asparaginase (PEG‐ASP) is preferred. Anaphylaxis with PEG‐ASP is rare. An 8‐year‐old girl and a 2.5‐year‐old boy, both diagnosed as having acute lymphoblastic leukemia, presented with native L‐asparaginase hypersensitivity and substitution with PEG‐ASP was preferred. They received a premedication (methylprednisolone, hydroxyzine and ranitidine) followed by desensitization with PEG‐ASP infusion. Both patients developed anaphylaxis with peg‐asparaginase. These are the first reported cases of anaphylactic reaction to PEG‐ASP, despite the application of both premedication and desensitization. Anaphylaxis with PEG‐ASP is very rare and premedication and desensitization protocols may not prevent these hypersensitive reactions.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号