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   3475154篇
  免费   297346篇
  国内免费   14134篇
耳鼻咽喉   47599篇
儿科学   109488篇
妇产科学   88247篇
基础医学   552097篇
口腔科学   93714篇
临床医学   314130篇
内科学   618823篇
皮肤病学   89668篇
神经病学   299675篇
特种医学   138898篇
外国民族医学   299篇
外科学   538431篇
综合类   106054篇
现状与发展   24篇
一般理论   2269篇
预防医学   294464篇
眼科学   79148篇
药学   239122篇
  24篇
中国医学   9610篇
肿瘤学   164850篇
  2021年   55919篇
  2020年   35503篇
  2019年   58687篇
  2018年   72046篇
  2017年   54823篇
  2016年   60667篇
  2015年   74759篇
  2014年   109320篇
  2013年   174549篇
  2012年   94275篇
  2011年   94086篇
  2010年   117517篇
  2009年   121948篇
  2008年   80954篇
  2007年   84121篇
  2006年   94617篇
  2005年   90093篇
  2004年   92003篇
  2003年   82721篇
  2002年   71728篇
  2001年   111202篇
  2000年   104805篇
  1999年   102349篇
  1998年   66311篇
  1997年   63919篇
  1996年   62101篇
  1995年   57848篇
  1994年   51838篇
  1993年   48431篇
  1992年   73606篇
  1991年   70282篇
  1990年   66615篇
  1989年   65172篇
  1988年   60418篇
  1987年   59095篇
  1986年   55910篇
  1985年   56013篇
  1984年   50479篇
  1983年   45795篇
  1982年   42588篇
  1981年   40000篇
  1980年   37689篇
  1979年   41792篇
  1978年   36578篇
  1977年   33123篇
  1976年   30481篇
  1975年   29039篇
  1974年   30278篇
  1973年   29038篇
  1972年   27041篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Do brain systems exist which control not only increases or decreases in food intake, but also bring about specific changes in the size and distribution of meals consumed, alter the selection of particular macronutrients and adjust feeding responses to the perceived pleasantness (hedonic value) of the food? A cautious yes can be given to each of these questions. Moreover, since most experimental work has been carried out on the brains of animals, we can also ask how well these animal data relate to the human condition; given the methodological issues involved in making such inferences, the answer is remarkably well.  相似文献   
992.
993.
【目的】探讨地塞米松的用药方式对孕妇糖代谢的影响。【方法】对 1999年 9月至 2 0 0 1年 1月在本院住院的15 0名不同用药方式使用地塞米松促胎儿肺成熟的孕妇进行研究 ,在用药前及用药后 18~ 2 4h抽取肘前静脉血查空腹血糖、血浆C肽 ,糖负荷后 2h血糖、血浆C肽。【结果】使用地塞米松后 ,空腹血糖值、糖负荷后 2h血糖值、空腹C肽及糖负荷后 2hC肽值较用药前高 ;用药方式对母体空腹血糖值和空腹C肽值的影响差异无统计学意义 (P >0 0 5 ) ,对母体糖负荷后 2h血糖值和糖负荷后 2hC肽值的影响差异有统计学意义 (P <0 0 5 ) ;不同糖代谢状态的受试者使用地塞米松后 ,空腹C肽值、糖负荷后 2hC肽值的改变差异有统计学意义 (P <0 0 5 )。【结论】孕妇使用地塞米松促胎儿肺成熟对母体的糖代谢均有一定程度的影响 ,用药过程中和用药后需严密监测母体血糖和胎儿宫内状况  相似文献   
994.
The optimal allocation of cadaveric kidneys for transplantation with reference to human leukocyte antigen (HLA) match and sharing these organs to a distant center remains controversial. The current analysis was performed using the United Network for Organ Sharing (UNOS) database for cadaveric kidney transplants (Tx) between 1988 and 1997. The graft survivals of zero-mismatch (matched) kidneys with the mate (mismatched) kidneys were compared. There were 2385 donors and 4770 Tx. Significant differences in recipient demographics between matched and mismatched Tx were: fewer African-American race (AA) in the matched group (9.0% vs. 21.9%), higher number of previous Tx (25.5% vs. 14.8%) and elevated mean cold ischemia time (24.0 vs. 22.2 h). Post-Tx dialysis requirements were similar (22.8% vs. 24.1%, p = 0.62) and matched kidneys had to travel more distance (920 vs. 232 miles). Using a Cox model, the matched group had a decreased relative hazard of graft failure of 23.0% (p = 0.0002) or 35% (p < 0.0001) with and without censoring for death. There was significantly better graft survival in the matched recipients in all pairs except AA (matched) and non-AA (mismatched). For older donors (> or = 50 years, n = 1508), the matched grafts survival was marginally significant (p =0.05). Matched kidneys have improved survival compared with the mismatched kidneys despite the longer distance traveled. The benefit of mismatched transplants was predominantly seen in non-AA.  相似文献   
995.
996.
The author describes a concept of automobilisation of the cervical spine and suboccipital joints. The well known biomechanic peculiarities of cervical spine are transformed in a therapeutic setting to allow a form of automobilisation within a closed system of head and underlying base. The so resulting new patterns of movement – the so-called “advanced movement”– differ from those usually exercised. Slow motion moving and low strength efforts are resulting in mobilisation of important vertebral and soft tissue structures.  相似文献   
997.
Prat  F. 《Acta endoscopica》2002,32(2):507-510
Acta Endoscopica - L’hémorragie iatrogène en endoscopie digestive reste pour l’essentiel l’apanage des techniques de résection tumorale et de la...  相似文献   
998.
999.
In standing, there are small sways of the body. Our interest is to use an artificial task to illuminate the mechanisms underlying the sways and to account for changes in their size. Using the ankle musculature, subjects balanced a large inverted pendulum. The equilibrium of the pendulum is unstable and quasi-regular sway was observed like that in quiet standing. By giving full attention to minimising sway subjects could systematically reduce pendulum movement. The pendulum position, the torque generated at each ankle and the soleus and tibialis anterior EMGs were recorded. Explanations about how the human inverted pendulum is balanced usually ignore the fact that balance is maintained over a range of angles and not just at one angle. Any resting equilibrium position of the pendulum is unstable and in practice temporary; movement to a different resting equilibrium position can only be accomplished by a biphasic 'throw and catch' pattern of torque and not by an elastic mechanism. Results showed that balance was achieved by the constant repetition of a neurally generated ballistic-like biphasic pattern of torque which can control both position and sway size. A decomposition technique revealed that there was a substantial contribution to changes in torque from intrinsic mechanical ankle stiffness; however, by itself this was insufficient to maintain balance or to control position. Minimisation of sway size was caused by improvement in the accuracy of the anticipatory torque impulses. We hypothesise that examination of centre of mass and centre of pressure data for quiet standing will duplicate these results.  相似文献   
1000.
BACKGROUND: The risk for allergic reactions depends on the sensitivity of individuals and the quantities of offending food ingested. The sensitivity varies among allergic individuals, as does the threshold dose of a food allergen capable of inducing an allergic reaction. OBJECTIVE: This study aimed at determining the distribution of minimum provoking doses of hazelnut in a hazelnut-allergic population. METHODS: Thirty-one patients with a history of hazelnut-related allergic symptoms, a positive skin prick test to hazelnut and/or an elevated specific IgE level, were included. Double-blind, placebo-controlled food challenges (DBPCFC) were performed with seven increasing doses of dried hazelnut (1 mg to 1 g hazelnut protein) randomly interspersed with seven placebo doses. RESULTS: Twenty-nine patients had a positive challenge. Itching of the oral cavity and/or lips was the first symptom in all cases. Additional gastrointestinal symptoms were reported in five patients and difficulty in swallowing in one patient. Lip swelling was observed in two patients, followed by generalized urticaria in one of these. Threshold doses for eliciting subjective reactions varied from a dose of 1 mg up to 100 mg hazelnut protein (equivalent to 6.4-640 mg hazelnut meal). Extrapolation of the dose-response curve showed that 50% of our hazelnut-allergic population will suffer from an allergic reaction after ingestion of 6 mg (95% CI, 2-11 mg) of hazelnut protein. Objective symptoms were observed in two patients after 1 and 1,000 mg, respectively. CONCLUSION: DBPCFCs demonstrated threshold doses in half of the hazelnut-allergic patients similar to doses previously described to be hidden in consumer products. This stresses the need for careful labelling and strategies to prevent and detect contamination of food products with hazelnut residues.  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