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   29672篇
  免费   2135篇
  国内免费   52篇
耳鼻咽喉   443篇
儿科学   1063篇
妇产科学   605篇
基础医学   4296篇
口腔科学   595篇
临床医学   3024篇
内科学   5577篇
皮肤病学   620篇
神经病学   2990篇
特种医学   1130篇
外国民族医学   12篇
外科学   3814篇
综合类   412篇
一般理论   27篇
预防医学   2664篇
眼科学   898篇
药学   1968篇
中国医学   51篇
肿瘤学   1670篇
  2023年   194篇
  2022年   376篇
  2021年   711篇
  2020年   449篇
  2019年   624篇
  2018年   693篇
  2017年   520篇
  2016年   582篇
  2015年   667篇
  2014年   801篇
  2013年   1106篇
  2012年   1608篇
  2011年   1628篇
  2010年   916篇
  2009年   779篇
  2008年   1287篇
  2007年   1413篇
  2006年   1278篇
  2005年   1312篇
  2004年   1222篇
  2003年   1041篇
  2002年   1130篇
  2001年   756篇
  2000年   768篇
  1999年   686篇
  1998年   323篇
  1997年   276篇
  1996年   261篇
  1995年   217篇
  1994年   196篇
  1993年   177篇
  1992年   457篇
  1991年   464篇
  1990年   440篇
  1989年   392篇
  1988年   399篇
  1987年   363篇
  1986年   370篇
  1985年   340篇
  1984年   278篇
  1983年   210篇
  1982年   164篇
  1979年   236篇
  1978年   175篇
  1977年   172篇
  1976年   155篇
  1975年   162篇
  1974年   186篇
  1973年   154篇
  1972年   156篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
3,4-Methylenedioxymethamphetamine damages fine serotonergic fibers and nerve terminals in adult organisms. Developing animals seem to be less susceptible to this effect, possibly due to a lack of drug-induced hyperthermia. We tested this hypothesis by producing hyperthermia in neonatal rats for 2 h after each of twice-daily MDMA (10 mg/kg s.c.) or saline injections administered from postnatal days 1–4. Other drug-treated and control litters were maintained at normothermic temperatures following injection. Changes in forebrain serotonergic innervation were assessed at postnatal day 25 (serotonin transporter binding and serotonin levels), postnatal day 60 (serotonin transporter binding), and 9 months of age (serotonin transporter immunohistochemistry). We also determined the influence of MDMA treatment on apoptotic activity by means of immunohistochemistry for cleaved caspase-3 at postnatal day 5. The hippocampus showed significant MDMA-related reductions in serotonergic markers at postnatal day 25 and postnatal day 60. At 9 months, there was no effect of prior MDMA exposure on serotonin transporter-immunoreactive fiber density in the hippocampus; however, significant reductions in fiber density were observed in two neocortical areas and a hyperinnervation was found in the caudate-putamen and nucleus accumbens shell. MDMA treatment also produced a two-fold increase in the number of cleaved caspase-3-immunoreactive cells in the rostral forebrain and hippocampus. All of these effects were completely independent of pup body temperature. These findings demonstrate that neonatal MDMA administration exposure stimulates apoptotic cell death in various forebrain areas and also leads to a long-term reorganization of the forebrain serotonergic innervation. Consequently, offspring of MDMA-using women may be at heightened risk for abnormal neural and behavioral development.  相似文献   
82.
Primary megaureter is a common cause of obstructive uropathy in children. The imaging studies and records of 75 infants and children with primary megaureter seen at Children's Hospital were reviewed. We describe our findings and illustrate the clinical presentations, diagnosis, and treatment of this entity.  相似文献   
83.
C Oursin  E Meyer 《Der Radiologe》1992,32(2):77-79
Soft tissue calcification is a well-known complication in chronic dialysis patients. These calcifications are mainly located around the large joints. Calcification of the visceral organs also occurs in these patients, even though this fact is far less known. These visceral calcifications are mostly diagnosed post mortem as they tend to be discrete and asymptomatic. In this article, we report on a chronic dialysis patient in whom extensive pulmonary calcifications occurred, leading to clinical symptoms.  相似文献   
84.
Few bureaucratic appointments have raised as many eyebrows as the announcement that controversial health economist Jane Fulton would become Alberta's deputy minister of health. A staunch supporter of private health care, Fulton joins the Alberta ministry just as Premier Ralph Klein's Progressive Conservatives gear up for a battle with Ottawa over two-tier medicine.  相似文献   
85.
86.
87.
Carotid body tumors: a subject review and suggested surgical approach   总被引:1,自引:0,他引:1  
Carotid body tumors are a rare but potentially difficult surgical entity. Their pathology, physiology, and natural history are reviewed along with surgical results reported in the literature. A surgical approach for removal of these tumors is presented which differs significantly from the recommended techniques in that emphasis is placed on intraoperative monitoring of cerebral blood flow, the the selective use of shunts, a tumor-adventitial plane of dissection, preservation of the carotid artery complex, and mobilization of the parotid gland. Thirteen cases using these techniques are reviewed. The mortality rate and the incidence of cerebrovascular sequelae were both 0%. The major morbidity consisted of injury to the lower cranial nerves in five patients (39%) with tumors larger than 5 cm in length.  相似文献   
88.
OBJECTIVE: To examine the association between socioeconomic position and coping strategies in musculoskeletal pain. DESIGN AND SUBJECTS: Cross-sectional study of a random sample of 40- and 50-year-old Danes, participation rate 69%, n=7,125. The study included 1,287 persons who reported functional limitations due to musculoskeletal pain. METHODS: Data was collected by postal questionnaires and scales were developed on problem-solving coping and avoidant coping, based on a range of preliminary studies. Multivariate logistic regression analyses was used to study the correlation with socioeconomic position, measured by occupational social class. RESULTS: Among women, there was no correlation between social class and avoidant coping, but a significant decrease in the use of problem-solving coping by decreasing social class, adjusted odds ratio (OR) = 2.64 (95% confidence interval (CI) 1.31-5.32) in social class V vs social classes I + II. Among men, there was no correlation between social class and problem-solving coping, but a significant increase in the use of avoidant coping with decreasing social class, adjusted OR = 3.31 (95% CI 1.75-6.25) in V vs I + II. CONCLUSION: It is important for clinicians who advise and support patients in their response to musculoskeletal pain to be aware of socioeconomic differences in coping strategies. Gender differences in the association between socioeconomic factors and coping should be further investigated.  相似文献   
89.
90.
The spontaneous reaction of 110 microM chlorambucil (4-[p-[bis(2-chloroethyl)amino]phenyl]-butanoic acid; CHB) with 5 mM GSH at 37 degrees C in physiological phosphate-buffered saline for 35 min gave primarily the monoglutathionyl derivative, 4-[p-[N-2-chloroethyl,N-2-S-glutathionylethyl]amino]phenyl]-butano ic acid; CHBSG) and the diglutathionyl derivative, 4-[p-[bis(2-S-glutathionylethyl]amino]phenyl]-butanoic acid (CHBSG2) with small amounts of the hydroxy-derivatives: 4-[p-[N-2-chloroethyl,N-2-hydroxy-ethyl]amino] phenyl-butanoic acid (CHBOH) and 4-[p-[N-2-S-glutathionylethyl-2-hydroxyethyl]amino]phenyl]-butanoi c acid (CHBSGOH). The inclusion of approximately physiological amounts of human glutathione S-transferases (GSTs) A1-1, A2-2, P1-1, M1a-1a M3-3 or P1-1 (for nomenclature see Mannervik et al., 1992, Biochem. J., 282, 305) had little or no catalytic effect on these reactions as determined by loss of CHB. However, GTSs A1-1 and A2-2 were associated with a significant increase of CHBSG at the expense of CHBSG2 + CHBSGOH suggesting that these GTs sequestered CHBSG at the active site. This interpretation was supported by inhibition studies which showed that CHBSG was a pure competitive inhibitor of the activity of GSTs A1-1 and A2-2 towards 1-chloro-2,4-dinitrobenzene with Ki's of 1.3 and 1.2 microM respectively. GSH transferases P1-1 and M1a-1a were inhibited by CHBSG above 10 microM. Incubation of 2 microM CHB, a concentration which may be of more significance for chemotherapy, in the presence or absence of GST A1-2 (20-50 microM) showed catalysis of GSH monoconjugation equivalent to 18% of the spontaneous rate. However, the dominant effect again was the sequestration of CHBSG which reached 74.3 +/- 1.5 (SEM)% of the total reactants at 60 min compared to 28.9 +/- 0.3(SEM)% in controls. CHBSG, although possessing a potential electrophilic centre, showed no detectable alkylation of plasmid DNA but indirect evidence was obtained that it alkylated other cellular macromolecules. It is concluded that the contribution of GSTs to catalysis of CHB detoxication will depend on factors not previously considered, namely the relative molarities of CHB, CHBSG and GSTs, and the cellular capacity to excrete CHBSG to relieve product inhibition.  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