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   1027564篇
  免费   69538篇
  国内免费   1571篇
耳鼻咽喉   14653篇
儿科学   33838篇
妇产科学   30462篇
基础医学   149812篇
口腔科学   28212篇
临床医学   86783篇
内科学   201781篇
皮肤病学   21123篇
神经病学   79623篇
特种医学   39841篇
外国民族医学   309篇
外科学   158376篇
综合类   21189篇
一般理论   221篇
预防医学   74046篇
眼科学   23268篇
药学   78096篇
  17篇
中国医学   1975篇
肿瘤学   55048篇
  2018年   9538篇
  2015年   9269篇
  2014年   12860篇
  2013年   19455篇
  2012年   26791篇
  2011年   28690篇
  2010年   16940篇
  2009年   15947篇
  2008年   27994篇
  2007年   30330篇
  2006年   30738篇
  2005年   30256篇
  2004年   29063篇
  2003年   28236篇
  2002年   27965篇
  2001年   46534篇
  2000年   47644篇
  1999年   40536篇
  1998年   11349篇
  1997年   10372篇
  1996年   10509篇
  1995年   9919篇
  1994年   9467篇
  1993年   8666篇
  1992年   32938篇
  1991年   32367篇
  1990年   31889篇
  1989年   30990篇
  1988年   28841篇
  1987年   28173篇
  1986年   26959篇
  1985年   25561篇
  1984年   19033篇
  1983年   16650篇
  1982年   9917篇
  1981年   8680篇
  1980年   8143篇
  1979年   18159篇
  1978年   12617篇
  1977年   10979篇
  1976年   10377篇
  1975年   11309篇
  1974年   13362篇
  1973年   12908篇
  1972年   12261篇
  1971年   11351篇
  1970年   10572篇
  1969年   10251篇
  1968年   9659篇
  1967年   8376篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Neuroscience and Behavioral Physiology - Objective. To assess the association of the DRD2 gene and its interaction with the HTR2C gene with the characteristics of the hedonistic and activatory...  相似文献   
92.
93.
94.
Neuroscience and Behavioral Physiology - One version of the optogenetic prosthetization of the degenerative retina is an approach based on creation of an ON/OFF receptive field for ganglion neurons...  相似文献   
95.
Neuroscience and Behavioral Physiology - Human behavior in conditions of partial indeterminacy of the outcome is characterized by correspondence between the frequency of actions and the probability...  相似文献   
96.

The cheetah (Acinonyx jubatus Brookes 1828) is classified as “vulnerable” by the International Union for Conservation of Nature (IUCN). Threats to cheetah populations are a decrease of suitable habitats, an increase of conflicts with livestock farmers and potentially pathogens. While there is some information on the viral and bacterial pathogens circulating in cheetah populations, information on gastrointestinal parasites is scarce. Here, we investigate the gastrointestinal parasites in 39 free-ranging cheetahs in east-central Namibia using a coproscopical parasitological method. Most cheetahs (82%) shed eggs from Ancylostoma which comprised the majority of the total eggs in feces. Eggs and oocysts from Toxascaris (21% of cheetahs), Coccidia (13%), Physaloptera (8%), Taeniidae (5%), Dipylidium (3%), and Diphyllobothriidae (3%) were present at a lower prevalence. Parasite richness and Ancylostoma egg load were higher in juveniles and adults compared to cubs, but were not associated with sex. To our knowledge, this is the first study that assessed gastrointestinal parasites in free-ranging cheetahs and is a key starting point for future studies on the effect of parasites in this threatened species.

  相似文献   
97.
Hendrickx  Sarah  Caljon  G.  Maes  L. 《Parasitology research》2019,118(10):2743-2752

Leishmaniasis is a neglected parasitic disease for which the current antileishmania therapeutics are hampered by drug toxicity, high cost, need for parenteral administration, increasing treatment failure rates, and emergence of drug resistance. The R&D pipeline had run fairly dry for several years, but fortunately some new drug candidates are now under (pre)clinical development. Identification of novel drugs will nevertheless remain essential to adequately sustain and improve effective disease control in the future. In this review, a package of standard and accessible R&D approaches is discussed with expansion to some alternative strategies focusing on parasite–host and vector–host interactions.

  相似文献   
98.
Faunal health is largely dependent on their soil environment and available litter quality. So the effects of different soil habitats and pesticides on citrate synthase (CS) activity of soil fauna and its population were studied. Methods The soil animals were collected from different pedoecosystems for habitat study. Whereas Vigna radiata based system was selected for pesticidal observations. The field was divided into five equal plots for control and treatment of γ-BHC, quinalphos, carbaryl and cypermethrin. Soil fauna was collected by quadrat method and extracted by Tullgren funnel. Individuals of a species having similar sizes were collected for the estimation of CS activity. They were homogenized and fractions were obtained by differential centrifugation. The activity of CS was assayed spectrophotometrically. Results Citrate synthase (CS) activity of beetle (Rasphytus fregi), woodlouse (PorceUio laevis) and centipede (Scolopendra morsitans) varied significantly with respect to changes in different soil habitats. Though the CS activity of R. fregi, P. laevis, and S. morsitans differed among themselves but the highest activity of CS in these animals was in V. radiata and lowest in A. nilotica based pedoecosystem. The aerobic capacity of centipede was maximum followed by woodlouse and beetle. The treatment of γ-BHC, quinalphos, carbaryl and cypermethrin significantly reduced the CS activity of these animals. γ-BHC showed maximum reduction in CS activity indicating highly toxic effect of organochlorine on aerobic metabolism of soil fauna. However, minimum reduction was obseryed in response to carbaryl (in beetle) or cypermethrin (in woodlouse/centipede) leading to impairment of aerobic capacity. The differences in pesticide effects might be assigned to the differences in chemical nature of pesticides and their interactions with below-ground fauna. Treatment ofγ-BHC and quinalphos reduced the population of Acari, Coleoptera, Collembola, other arthropods as well as total soil fauna. Acari was least affected by γ-BHC and maximally affected (72%) in response to quinalphos. The effect of γ-BHC was fairly similar on Coleoptera, Collembola, other arthropod and total soil fauna suggesting almost similar sensitivity to this pesticide. Likewise, quinalphos was similarly effective on Collemobola and other soil arthropods. Application of carbaryl decreased Acari and Coleoptera population but increased Collembola, other arthropods and total faunal populations. However, application of cypermethrin significantly reduced the population of Acari, Coleoptera, Collembola and total soil fauna and increased the population of other soil arthropods. In both the cases, acarine population was least affected. Conclusion The observations show the habitat-specific variation in aerobic capacity of soil fauna. However, pesticide-dependent loss in population might be due to impairment of aerobic capacity of soil inhabiting animals in desert.  相似文献   
99.
International Journal of Clinical Pharmacy - Background Pharmacists are increasingly involved in patient care. This new role in a complex healthcare system with demanding patients may lead to moral...  相似文献   
100.
Objective The purpose of this study was to examine the content of the first prenatal visit within an academic medical center clinic and to compare the topics discussed to 2014 American College of Obstetrics and Gynecologists guidelines for the initial prenatal visit. Methods Clinical interactions were audio recorded and transcribed (n?=?30). A content analysis was used to identify topics discussed during the initial prenatal visit. Topics discussed were then compared to the 2014 ACOG guidelines for adherence. Coded data was queried though the qualitative software and reviewed for accuracy and content. Results First prenatal visits included a physician, nurse practitioner, nurse midwife, medical assistant, medical students, or a combination of these providers. In general, topics that were covered in most visits and closely adhered to ACOG guidelines included vitamin supplementation, laboratory testing, flu vaccinations, and cervical cancer screening. Topics discussed less often included many components of the physical examination, education about pregnancy, and screening for an identification of psychosocial risk. Least number of topics covered included prenatal screening. Conclusions for Practice While the ACOG guidelines may include many components that are traditional in addition to those based on evidence, the guidelines were not closely followed in this study. Identifying new ways to disseminate information during the time constrained initial prenatal visit are needed to ensure improved patient outcomes.  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