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   19806篇
  免费   807篇
  国内免费   124篇
耳鼻咽喉   171篇
儿科学   428篇
妇产科学   360篇
基础医学   2203篇
口腔科学   746篇
临床医学   1960篇
内科学   4175篇
皮肤病学   404篇
神经病学   1250篇
特种医学   443篇
外国民族医学   5篇
外科学   2509篇
综合类   489篇
一般理论   14篇
预防医学   1600篇
眼科学   758篇
药学   1842篇
  11篇
中国医学   220篇
肿瘤学   1149篇
  2024年   182篇
  2023年   316篇
  2022年   705篇
  2021年   1153篇
  2020年   796篇
  2019年   912篇
  2018年   1030篇
  2017年   738篇
  2016年   789篇
  2015年   797篇
  2014年   1071篇
  2013年   1243篇
  2012年   1685篇
  2011年   1739篇
  2010年   1019篇
  2009年   775篇
  2008年   1129篇
  2007年   1006篇
  2006年   839篇
  2005年   722篇
  2004年   563篇
  2003年   456篇
  2002年   397篇
  2001年   49篇
  2000年   58篇
  1999年   58篇
  1998年   50篇
  1997年   45篇
  1996年   43篇
  1995年   35篇
  1994年   18篇
  1993年   33篇
  1992年   24篇
  1991年   17篇
  1990年   19篇
  1989年   20篇
  1988年   17篇
  1987年   10篇
  1986年   13篇
  1985年   12篇
  1984年   19篇
  1983年   17篇
  1982年   16篇
  1981年   12篇
  1980年   12篇
  1979年   13篇
  1978年   10篇
  1976年   10篇
  1974年   8篇
  1973年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
We report the destructive adsorption of Diazinon pesticide by porous webs of activated carbon nanofibers containing Al2O3 and MgO nanoparticles. The results show that, the presence of Al2O3 and MgO nanoparticles in the activated carbon nanofibers increases the amount of destructively adsorbed Diazinon pesticide by activated carbon nanofibers. Moreover, type, amount, and specific surface area of metal oxide nanoparticles affect the adsorption rate as well as the total destructively adsorbed Diazinon. Liquid chromatography proved the degradation of Diazinon by chemical reaction with Al2O3 and MgO nanoparticles. Liquid chromatography–mass spectrometry showed that the main product of reaction between Diazinon and the metal oxides is 2-isopropyl-6-methyl-4-pyrimidinol with less toxicity than Diazinon.  相似文献   
82.
Tissue factor (TF) is a membranous glycoprotein that functions as a receptor for coagulation factor VII/VIIa and activates the coagulation system when blood vessels or tissues are damaged. TF was upregulated in our monocrotaline (MCT)/lipopolysaccharide (LPS) hepatotoxicity model. We tested the hypothesis that TF‐dependent fibrin deposition and lipid peroxidation in the form of oxidized low‐density‐lipoprotein (ox‐LDL) accumulation contribute to liver inflammation induced by MCT/LPS in mice. In the present study, we blocked TF using antisense oligodeoxynucleotides against mouse TF (TF‐ASO). TF‐ASO (5.6 mg kg?1) was given i.v. to ND4 male mice 30 min after administration of MCT (200 mg kg?1) p.o. followed after 3.5 h by LPS i.p. (6 mg kg?1). Blood alanine aminotransferase (ALT), TF, ox‐LDL, platelets, hematocrit and keratinocyte‐derived chemokine (KC) levels were evaluated in different treatment groups. Fibrin deposition and ox‐LDL accumulation were also analyzed in the liver sections using immunofluorescent staining. The results showed that TF‐ASO significantly restored blood ALT, hematocrit and KC levels, distorted after MCT/LPS co‐treatment, as well as preventing the accumulation of ox‐LDL and the deposition of fibrin in the liver tissues, and thereby inhibited liver injury caused by MCT/LPS. In a separate experiment, TF‐ASO administration significantly prolonged animal survival. The current study demonstrates that TF is associated with MCT/LPS‐induced liver injury. Administration of TF‐ASO successfully prevented this type of liver injury. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
83.
The primary diagnosis of Tuberculosis (TB) is usually carried out by looking at the various signs and symptoms of a patient. However, these signs and symptoms cannot be measured with 100 % certainty since they are associated with various types of uncertainties such as vagueness, imprecision, randomness, ignorance and incompleteness. Consequently, traditional primary diagnosis, based on these signs and symptoms, which is carried out by the physicians, cannot deliver reliable results. Therefore, this article presents the design, development and applications of a Belief Rule Based Expert System (BRBES) with the ability to handle various types of uncertainties to diagnose TB. The knowledge base of this system is constructed by taking experts’ suggestions and by analyzing historical data of TB patients. The experiments, carried out, by taking the data of 100 patients demonstrate that the BRBES’s generated results are more reliable than that of human expert as well as fuzzy rule based expert system.  相似文献   
84.
Current paper reviews the pharmacological activities, therapeutic indications and phytochemicals of M. longifolia. This herb has been consumed traditionally for the treatment of various diseases, including gastrointestinal disorders, respiratory disorders, infectious diseases, inflammatory diseases, as well as menstrual disorders. In the modern era, various pharmacological activities have been confirmed for M. longifolia, such as anti-parasitic, antimicrobial, anti-insect, antimutagenic, antinociceptive, anti-inflammatory, antioxidant, keratoprotective, hepatoprotective, anti-diarrhea, and spasmolytic effects. The plant showed therapeutic benefits in irritable bowel syndrome, amenorrhea and oligomenorrhea, and oxidative stress-associated diseases as well. A vast variety of natural components such as flavonoids, phenolic acids, cinnamates, ceramides, sesquiterpenes, terpenes, and terpenoids have been suggested to be responsible for the pharmacological action of M. longifolia. These natural products can be considered as novel medicinal sources for developing new drugs. Further investigations to explore therapeutic efficacy, tolerability, and pharmaceutical properties of M. longifolia phytochemical agents are recommended.  相似文献   
85.
Malignant melanoma is notorious for distant metastases. Median survival for stage IV melanoma is 6-10 months and 5 year survival is less than 5%. Median survival for melanoma with brain metastases is even lower i.e. 2 to 9 months. Here a case is reported who was treated for melanoma of sole of left foot with ipsilateral inguinal adenopathy and brain metastases in 2001 and is still surviving disease-free after a lapse of 8 years.  相似文献   
86.
The objective of this study was to examine the public health relevance of the prevalence of dental fear in Kuwait and the resultant barrier that it creates regarding access to dental care. The study analysis demonstrated a high prevalence of dental fear and anxiety in the Kuwaiti population and a perceived need for anesthesia services by dental care providers. The telephone survey of the general population showed nearly 35% of respondents reported being somewhat nervous, very nervous, or terrified about going to the dentist. In addition, about 36% of the population postponed their dental treatment because of fear. Respondents showed a preference to receive sedation and anesthesia services as a means of anxiety relief, and they were willing to go to the dentist more often when such services were available. People with high fear and anxiety preferred to receive some type of medication to relieve their anxiety. In conclusion, the significance and importance of the need for anesthesia services to enhance the public health of dental patients in Kuwait has been demonstrated, and improvements are needed in anesthesia and sedation training of Kuwaiti dental care providers.  相似文献   
87.
The aim of this study was to observe the histological features of chronic gastritis and associated effects due to Helicobacter pylori infection in 176 randomly selected antral biopsy specimens of chronic gastritis cases. The specimens were reviewed for the presence or absence of H.pylori. The activity (neutrophilic infiltration) of gastritis and the presence or absence of mucosa-associated lymphoid tissue (MALT) were also noted. Chi-square test (Pearson value) was used to analyze categorical variables. H.pylori was detected in 110 (62.5%) cases of chronic gastritis. There was a significant association between H.pylori infection and activity of chronic gastritis (p=0.002). Lymphoid aggregates were significantly more frequently noted in H.pylori-positive patients (68.2%) vs. H.pylori negative group (47%), (p=0.005). It is concluded that H.pylori is significantly associated with active chronic gastritis and with formation of mucosa-associated lymphoid tissue (MALT), which may develop into gastric lymphoma (MALT type).  相似文献   
88.
Ruptured abdominal aorta aneurysm (rAAA) is the 13th leading cause of death in the United States. Despite many advances in the field of vascular surgery, the improvement in mortality rates of rAAA have been very modest. Although endovascular repair has surpassed open repair for elective AAA repair in the United States, open rAAA repair remains the most common therapy for this devastating vascular emergency. In this article, we discuss open surgical management for rAAA. We also describe a fast-track algorithm we have developed at the University of Massachusetts where open and endovascular repairs play equally important roles in management of rAAA.  相似文献   
89.
Melatonin, the major hormone produced by the pineal gland, is shown to have anticonvulsant effects. Nitric oxide (NO) is a known mediator in seizure susceptibility modulation. In the present study, the involvement of NO pathway in the anticonvulsant effect of melatonin in pentylenetetrazole (PTZ)-induced clonic seizures was investigated in mice. Acute intraperitoneal administration of melatonin (40 and 80 mg/kg) significantly increased the clonic seizure threshold induced by intravenous administration of PTZ. This effect was observed as soon as 1 min after injection and lasted for 30 min with a peak effect at 3 min after melatonin administration. Combination of per se non-effective doses of melatonin (10 and 20 mg/kg) and nitric oxide synthase (NOS) substrate L-arginine (30, 60 mg/kg) showed a significant anticonvulsant activity. This effect was reversed by NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg), implying an NO-dependent mechanism for melatonin effect. Pretreatment with L-NAME (30 mg/kg) and N(G)-nitro-L-arginine (L-NNA, 10 mg/kg) inhibited the anticonvulsant property of melatonin (40 and 80 mg/kg) and melatonin 40 mg/kg, respectively. Specific inducible NOS (iNOS) inhibitor aminoguanidine (100 and 300 mg/kg) did not affect the anticonvulsant effect of melatonin, excluding the role of iNOS in this phenomenon, while pretreatment of with 7-NI (50 mg/kg), a preferential neuronal NOS inhibitor, reversed this effect. The present data show an anticonvulsant effect for melatonin in i.v. PTZ seizure paradigm, which may be mediated via NO/L-arginine pathway by constitutively expressed NOS.  相似文献   
90.
PURPOSE: To compare the efficacy and safety of dapoxetine, paroxetine, and placebo for the oral pharmacotherapy of premature ejaculation. MATERIALS AND METHODS: Three hundred forty potent men with premature ejaculation were recruited to this study. Patients were randomly assigned to receive 60 mg dapoxetine (group 1, n = 115), or 20 mg paroxetine (group 2, n = 113) or placebo (group 3, n = 112) orally daily during a 12-week period for each agent. The efficacy of the 3 treatments was assessed every 2 weeks during treatment and at the end of study using responses to International Index of Erectile Function (IIEF), intravaginal ejaculatory latency time (IELT) evaluation, mean intercourse satisfaction domain, mean weekly coitus episodes and adverse drug effects. RESULTS: At the end of the 12-week treatment with dapoxetine, paroxetine, and placebo, the mean IELT was increased from 38, 31 and 34 seconds to 179, 370 and 55 seconds, respectively (P = 0.01 in group 1 and P = 0.001 in group 2). Baseline mean intercourse satisfaction domain values of International Index of Erectile Function of 10, 11, and 11 reached 14, 17 and 12 at the end of the 12-week treatment in groups 1, 2, and 3 respectively (P = 0.03 in groups 1, 2). The mean weekly intercourse episodes increased from pretreatment values of 1.4, 1.3, and 1.3 to 2.2, 2.5 and 1.4, for dapoxetine, paroxetine and placebo, respectively (P = 0.04 in groups 1, 2). The incidence of adverse effects with dapoxetine and paroxetine was significantly higher (P = 0.04 in groups 1, 2) compared to that of placebo. CONCLUSIONS: Paroxetine appears to provide significantly better results in terms of IELT and intercourse satisfaction versus dapoxetine. Each treatment was well tolerated.  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