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   3422篇
  免费   166篇
  国内免费   9篇
耳鼻咽喉   68篇
儿科学   69篇
妇产科学   37篇
基础医学   368篇
口腔科学   235篇
临床医学   293篇
内科学   806篇
皮肤病学   8篇
神经病学   279篇
特种医学   100篇
外科学   646篇
综合类   31篇
一般理论   2篇
预防医学   240篇
眼科学   16篇
药学   213篇
肿瘤学   186篇
  2023年   12篇
  2022年   24篇
  2021年   54篇
  2020年   29篇
  2019年   45篇
  2018年   52篇
  2017年   46篇
  2016年   70篇
  2015年   89篇
  2014年   96篇
  2013年   152篇
  2012年   221篇
  2011年   242篇
  2010年   132篇
  2009年   149篇
  2008年   240篇
  2007年   235篇
  2006年   232篇
  2005年   182篇
  2004年   162篇
  2003年   174篇
  2002年   159篇
  2001年   27篇
  2000年   28篇
  1999年   26篇
  1998年   36篇
  1997年   37篇
  1996年   29篇
  1995年   41篇
  1994年   40篇
  1993年   26篇
  1992年   27篇
  1991年   30篇
  1990年   25篇
  1989年   24篇
  1988年   30篇
  1987年   22篇
  1986年   27篇
  1985年   38篇
  1984年   31篇
  1983年   26篇
  1982年   19篇
  1981年   21篇
  1980年   20篇
  1979年   19篇
  1978年   19篇
  1977年   21篇
  1976年   14篇
  1975年   13篇
  1973年   10篇
排序方式: 共有3597条查询结果,搜索用时 15 毫秒
11.
Summary A search was made for patients with associated secondary hyperparathyroidism and hypercalcemia: 22 such cases were found in the literature and 22 were recorded among 92 patients operated upon because of parathyroid disease. In the remaining 70 patients the effect of the operation on the serum calcium level was investigated: persisting hypercalcemia after the operation was found in 28 per cent of the cases.The patients reporded in the literature possessed severe renal and skeletary changes and light microscopic evidence of parathyroid adenoma (2 cases), hyperplasia (15 cases), or hyperplasia and adenoma (5 cases).The other 22 patients had histories of long-standing renal disease, most often chronic pyelonephritis, of varying severity. Skeletary roentgenograms were often normal. Morphologic examination of the parathyroids showed adenoma (6 cases) or hyperplasia (16 cases). Postoperatively, normal serum calcium level was found in 9 cases and persisting hypercalcemia in 13 (=59 per cent) cases. One patient possessed also a malignant -cell insuloma and Zollinger-Ellison's syndrome.It is suggested that secondary hyperparathyroidism may develop in patients with only slight or moderate impairment of renal function, that hypercalcemia occurs more often than previously believed in secondary hyperparathyroidism, and that some cases of secondary hyperparathyroidism previously, erroneously have been classified as primary hyperparathyroidism.Supported by grants from the Swedish Medical Research Council (Project No. B72-17X-3499-01), the Swedish Cancer Society (Project No. 552-B71-01P), and the Medical Faculty, University of Umeå.  相似文献   
12.
In vitro cell culture models can be of great value in order to further analyze the regulatory mechanisms underlying the inappropriate function of the immune system in diseases such as autoimmunity and cancer. Cell culture conditions have to be well controlled in a way that they mirror the in vivo situation. The objective of this study was to compare tissue culture microtiter plates from different manufacturers with respect to their ability to support monokine production by human monocytes cultured in human serum. Tissue culture ware, made of polystyrene, undergoes treatment by the manufacturers to make the surface more suitable for culture of adherent cell populations. It is possible that quality differences in this treatment can lead to variations in protein binding properties and thereby influence the adherence and functional properties of monocytes. We measured spontaneous interleukin-1 receptor antagonist (IL-1ra) production by peripheral blood monocytes, cultured in human serum, in five different microtiter plates made for adherent cell culture. Culture in plates from two of the five manufacturers resulted in significantly lower amounts of secreted IL-1ra. IL-1ra release by human monocytes can be induced by adherent IgG cross-linking membrane receptors for the Fc part of IgG (FcgammaR). We found that reduced IL-1ra production coincided with a reduced capacity for binding of serum IgG in one case. Furthermore, this brand of microtiter plate also displayed the lowest level of adsorption of human albumin. We conclude that the protein adsorption properties of the plastic tissue culture ware have to be taken into consideration when assessing monokine production by human monocytes in vitro.  相似文献   
13.
ZK 91296, a partial agonist at benzodiazepine receptors   总被引:2,自引:0,他引:2  
ZK 91296 (ethyl 5-benzyloxy-4-methoxymethyl--carboline-3-carboxylate) is a potent and selective ligand for benzodiazepine (BZ) receptors. Biochemical investigations indicate that ZK 91296 may be a partial agonist at BZ receptors. Such partial agonism may explain to some extent why ZK 91296 needs higher BZ receptor occupancy than diazepam for the same effect against chemical convulsants and for behavioural effects. The lack of sedatiye effects, and the very potent inhibition of reflex epilepsy, spontaneous epilepsy and DMCM-induced seizures suggest, furthermore, that ZK 91296 may possess pharmacological selectivity for a particular type of BZ receptor interaction, perhaps including topographic as well as receptor subtype differentiation.  相似文献   
14.

Sociosexuality and sexual compulsivity predict sex differences in voyeuristic interest in the population. In this study, we used a sample of 1113 participants from the UK (46% men) to consider whether sociosexuality and sexual compulsivity interacted to explain these sex differences and whether this relationship extended to the related domain of exhibitionism. In doing so, we tested novel predictions derived from an evolutionary perspective which views voyeuristic and exhibitionistic interest as manifestations of a short-term mating strategy. Participants reported their levels of repulsion toward voyeurism and exhibitionism and their interest in performing such acts under different levels of risk. There were clear sex differences in voyeuristic and exhibitionistic repulsion that were partially mediated by the serial combination of sociosexuality and sexual compulsivity. Examining the sexes separately revealed qualitatively different relationships between sociosexuality and sexual compulsivity when predicting exhibitionistic, but not voyeuristic, repulsion. Combined, sociosexuality and sexual compulsivity also mediated the sex difference in willingness to commit acts of voyeurism, but not exhibitionism, which was equally low for both sexes. The results highlight the role sociosexuality plays in voyeuristic and exhibitionistic interest, which coupled with an evolutionary perspective, may have implications for how we view courtship disorders.

  相似文献   
15.
Chlorohydroxyfuranones (CHFs) are mutagenic disinfection by-productsfound in chlorine-treated drinking water. In the current study,the genotoxicity of four CHFs, 3,4-dichloro-5-hydroxy-2(5H)-furanone(MCA), 3-chloro-4-methyl-5-hydroxy-2(5H)-furanone (MCF), 3-chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone(CMCF) and 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone(MX), was determined. Two in vitro assays, the microscale micronucleusassay on L5178Y mouse lymphoma cells and the unscheduled DNAsynthesis assay on a hepatocyte primary culture from FisherF344 rats, were carried out. All four CHFs demonstrated genotoxiceffects in both assays. In the two systems used, CMCF was themost genotoxic compound, followed by MCA, MX and MCF, respectively.This work was the first study of the DNA damaging propertiesof all four CHFs in two in vitro genotoxicity tests. These newdata expand the range of genetic damages induced by this groupof compounds. 2 To whom correspondence should be addressed. Tel: +33 3 20 8779 14; Fax: +33 3 20 87 73 10; Email: daniel.marzin{at}pasteur-lille.fr  相似文献   
16.
BACKGROUND: A prospective randomized multicentre study was performed to compare the outcome of laparoscopic and open appendicectomy in patients with suspected acute appendicitis. METHODS: A total of 523 patients was randomized, but because of 23 withdrawals the outcome in 500 patients is reported, 244 in the laparoscopic group and 256 in the open group. RESULTS: Patients having laparoscopic appendicectomy recovered more quickly than those having open surgery (13 versus 21 days, P < 0.001). There was no significant difference in duration of sick leave after operation (laparoscopic group 11 days versus open group 14 days). Postoperative pain (at 24 h, 7 days and 14 days) was less after laparoscopic operations and a functional index 1 week after operation was more favourable in these patients (P < 0.001). Operating time was significantly longer in the laparoscopic group (60 versus 35 min, P < 0.01). Hospital stay and complications did not differ between the groups. Thirty laparoscopic procedures (12 per cent) were converted to open appendicectomy. CONCLUSION: Laparoscopic appendicectomy is as safe as open appendicectomy and has the advantage of allowing a quicker recovery.  相似文献   
17.
Rats were treated chronically with -methyl-p-tyrosine methyl-ester HCl (-MT) twice daily for 0–14 days. At 1 h after the (last) -MT injection, d-amphetamine sulphate was given and motor activity was measured in an ANIMEX activity meter for 4 h. Amphetamine-induced excitatory and stereotyped behaviour was scored according to a rating scale in a separate experiment. A single dose of -MT markedly reduced the activity response after amphetamine. After 1–3 days of -MT treatment, tolerance to its amphetamine-antagonistic affect started to develop, reaching a maximal degree after 7–14 days. The pattern of the amphetamine response, monophasic in control rats, became biphasic in the -MT tolerant rats with an early (at 0–1 h) and a late (2–4 h) peak of motor activity. The late peak appeared within 3 days, while the early peak appeared after 7 days of -MT treatment. The results on amphetamine-induced excitatory and stereotyped behaviour in essence agreed with the motor-activity data. It is concluded that tolerance to the amphetamine-antagonistic action of -MT is not complete. Its rate of development varies in a complex pattern, indicating the presence of more than one mechanism of tolerance.  相似文献   
18.
Regional cerebral blood flow (CBF) was studied tomographically with 133Xe administered by inhalation over a 1-min period at a concentration of 10 mCi/l. A fast rotating (dynamic) single-photon emission computed tomograph with four detector heads was used, an instrument that has been found to be well suited for detecting focal ischemia. In the present study its ability to detect focal hyperemia was investigated in 13 normal subjects studied during rest and during visual stimulation. A flickering light seen with eyes open and closed, increased blood flow in the visual cortex by 35% and 22% respectively. Looking at different pictures displayed on a screen raised regional CBF by 26%. The most complex task, reading and copying a text, increased blood flow by 45%. Averaging the different tasks resulted in a mean regional CBF increase in the visual cortex of 35%. The result is comparable with that obtained by positron emission tomography. Both forms of isotope tomography offer unique possibilities for the study of brain function in health and disease, possibilities not matched by X-ray tomography. The low cost and ready availability of appropriate single-photon radionucleides (133Xe and 127Xe) are mentioned.Supported by the Danish Medical Research Council, the Danish Sclerose Association, and the Johann and Hanne Weimann Foundation.  相似文献   
19.
Mice in experimental delay of implantation were injected intravenously with 75 g · g–1 body weight of lead chloride, corresponding to a dose of lead of about 56 g · g–1 body weight. Delay of implantation was obtained by ovariectomy 3 days after mating followed by a depot dose of progesterone every fifth day. Electron microscopy showed that the uterine lumen, which was closed in control mice, was opened in lead-injected mice. This morphology suggested that lead caused an increase in uterine secretion. X-ray microanalysis of pyroantimonate precipitates in the uterine epithelium of injected mice demonstrated lead in the precipitates, suggesting that lead could have a direct effect on the function of the uterine epithelium and that lead also could be secreted into the uterine lumen and affect the blastocysts.  相似文献   
20.
OBJECTIVEIn a large, multiethnic cohort of youths with obesity, we analyzed pathophysiological and genetic mechanisms underlying variations in plasma glucose responses to a 180 min oral glucose tolerance test (OGTT).RESEARCH DESIGN AND METHODSLatent class trajectory analysis was used to identify various glucose response profiles to a nine-point OGTT in 2,378 participants in the Yale Pathogenesis of Youth-Onset T2D study, of whom 1,190 had available TCF7L2 genotyping and 358 had multiple OGTTs over a 5 year follow-up. Insulin sensitivity, clearance, and β-cell function were estimated by glucose, insulin, and C-peptide modeling.RESULTSFour latent classes (1 to 4) were identified based on increasing areas under the curve for glucose. Participants in class 3 and 4 had the worst metabolic and genetic risk profiles, featuring impaired insulin sensitivity, clearance, and β-cell function. Model-predicted probability to be classified as class 1 and 4 increased across ages, while insulin sensitivity and clearance showed transient reductions and β-cell function progressively declined. Insulin sensitivity was the strongest determinant of class assignment at enrollment and of the longitudinal change from class 1 and 2 to higher classes. Transitions between classes 3 and 4 were explained only by changes in β-cell glucose sensitivity.CONCLUSIONSWe identified four glucose response classes in youths with obesity with different genetic risk profiles and progressive impairment in insulin kinetics and action. Insulin sensitivity was the main determinant in the transition between lower and higher glucose classes across ages. In contrast, transitions between the two worst glucose classes were driven only by β-cell glucose sensitivity.  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