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   17979篇
  免费   1369篇
  国内免费   69篇
耳鼻咽喉   148篇
儿科学   675篇
妇产科学   365篇
基础医学   2664篇
口腔科学   294篇
临床医学   1839篇
内科学   4075篇
皮肤病学   240篇
神经病学   1968篇
特种医学   622篇
外国民族医学   3篇
外科学   2295篇
综合类   231篇
一般理论   7篇
预防医学   1151篇
眼科学   660篇
药学   836篇
中国医学   14篇
肿瘤学   1330篇
  2021年   204篇
  2019年   241篇
  2018年   282篇
  2017年   226篇
  2016年   263篇
  2015年   278篇
  2014年   360篇
  2013年   530篇
  2012年   777篇
  2011年   831篇
  2010年   475篇
  2009年   450篇
  2008年   674篇
  2007年   821篇
  2006年   785篇
  2005年   738篇
  2004年   763篇
  2003年   666篇
  2002年   708篇
  2001年   613篇
  2000年   599篇
  1999年   478篇
  1998年   212篇
  1997年   185篇
  1996年   161篇
  1995年   176篇
  1994年   163篇
  1993年   147篇
  1992年   436篇
  1991年   413篇
  1990年   405篇
  1989年   362篇
  1988年   360篇
  1987年   341篇
  1986年   354篇
  1985年   315篇
  1984年   270篇
  1983年   228篇
  1982年   166篇
  1981年   162篇
  1980年   139篇
  1979年   219篇
  1978年   188篇
  1977年   136篇
  1976年   139篇
  1975年   141篇
  1974年   166篇
  1973年   163篇
  1972年   133篇
  1971年   131篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Leukemic cells from a series of patients with chronic B-lymphocytic leukemia (CLL) were analyzed for their buoyant density on discontinuous Percoll gradients. The density profile varied markedly between different patients and also between samples from different body compartments within the same patient. A good correlation was observed between buoyant density and maturation stage of the leukemic clones as judged by Ig-expression and their reactivity with a panel of monoclonal antibodies. Phorbol-ester-induced changes in the leukemic cells were found to be accompanied by a general decrease in their buoyant density. No correlation between density and clinical parameters such as cell counts, clinical stage and survival could be noted. Buoyant density characterization of leukemic B-cell populations is seen as a useful, rapid and simple marker of compartmentalization within the B-lymphocyte maturation spectrum but its clinical relevance remains to be established.  相似文献   
82.
Zusammenfassung Eine hochgradige Duodenalstenose im Erwachsenenalter kann in seltenen Fällen angeboren sein und findet ihre Ursache in einer intraduodenal gelegenen Membran. Die Anamnese zeigt Wachstumsstörungen mit Erbrechen und Meteorismus und abdominelle Beschwerden. Eine Perforationsöffnung in dieser Membran ist die Ursache fur ein Überleben bis ins Erwachsenenalter. Die Röntgendarstellung und die tiefe Duodenoskopie lassen auf einfache Weise die Diagnose stellen. Differentialdiagnostisch müssen der Volvulus bei Malrotation, Ladd-Bänder und das Pancreas anulare, sowie die Kompression des Duodenums durch Mesenterialgefäße erwogen werden. Das operative Verfahren der Wahl ist die Resektion der intraduodenalen Membran. Dabei ist v. a. die Papilla Vateri darzustellen, da diese nicht selten im Bereich des Septums mündet. Das längs eröffnete Duodenum wird quer verschlossen. Bei der Wind-Sock-Web-Anomalie sollte das Duodenum an der Ansatzstelle des Diaphragmas eröffnet werden. Die Anlage einer Gastrojejunostomie ist inadäquat und zu vermeiden.
Congenital duodenal stenosis in adulthood
A high-grade duodenal stenosis in adults can, in rare cases, be congenital, and its cause is found in an intraduodenally sited membrane. The anamnesis reveals growth disorders with vomiting and meteorism and abdominal complaints. A perforation opening in this membrane is the reason for survival into adulthood. The X-ray appearance and deep duodenoscopy make the diagnosis easy. Volvulus in cases of malrotation, Ladd's ligaments, anular pancreas, and compression of the duodenum by mesenteric vessels must be considered in the differential diagnosis. When the intraduodenal membrane is resected it is most important to expose the papilla Vateri, since this not uncommonly ends in the area of the septum. If necessary, a duodenoduodenostomy is performed. If the windsock web abnormality is present the duodenum should be opened at the point of attachment of the diaphragm. The construction of a gastrojejunostomy should be avoided.
  相似文献   
83.
OBJECTIVE: To compare the clinical efficacy and safety of trimethoprim-sulfamethoxazole (TMP-SMX) with pentamidine in the therapy of Pneumocystis carinii pneumonia (PCP) in patients with AIDS. PATIENTS, PARTICIPANTS: TMP-SMX (TMP, 20 mg/kg/day plus SMX, 100 mg/kg/day) was compared with pentamidine (4 mg/kg/day), both administered intravenously for 21 days in a prospective randomized treatment trial of 163 patients diagnosed with PCP between November 1984 and May 1988. RESULTS: Ninety-two evaluable patients received TMP-SMX as initial therapy; 68 received pentamidine. Failure to complete therapy was common. Of those receiving TMP-SMX, 39 (42%) required change in therapy because of failure to respond, and an additional 31 (34%) because of drug toxicity. This compared with 27 (40%; P = 0.733) and 17 (25%; P = 0.235), respectively, in the pentamidine-treated group. The overall survival rates were similar in the two groups, 62 out of 92 (67%) initially administered TMP-SMX versus 50 out of 68 (74%) initially administered pentamidine (P = 0.402). The survival rates for patients requiring a change in therapy because of failure to respond was 46% (18 out of 39) for the TMP-SMX group compared with 56% (15 out of 27) for the pentamidine group. When a change in therapy was made because of toxicity, survival rates were 97% (30 out of 31) for those receiving TMP-SMX versus 94% (16 out of 17) for those receiving pentamidine. CONCLUSION: TMP-SMX and pentamidine are of equivalent efficacy as initial therapies for PCP in patients with AIDS.  相似文献   
84.
It has been shown earlier that dilated cardiomyopathy can be associated withBorrelia burgdorferi infection.Here the authors present a case: a fifty-nine-year-old man who presented with dyspnea, oligoarthritis, paresthesia in both hands, and acrodermatitis chronica atrophicans. Upon further cardiologic exploration by cardiac catheterization and two-dimensional echocardiography (volume-length-area method), the patient exhibited an ejection fraction (EF) of 49%. Serology revealed IgG ELISA positive and IIFT 1:64 positive forB. burgdorferi. The patient received 2 × 150 mg roxithromycin orally for six weeks. Upon a second examination after termination of treatment (three months later), the patient presented with negativeB. burgdorferi serology and normal EF (70%). While cardiac manifestations thus apparently vanished, other symptoms persisted.This case may give new insight into mechanisms of action of macrolides againstB. burgdorferi (a field where information is inherently scant). One may, however, argue that in a well-perfused organ like the heart, tissue-activity of roxithromycin may suffice in order to unfold its activity againstB. burgdorferi.  相似文献   
85.
86.
Parkin mutations account for the majority of familial and sporadic early onset Parkinson's disease (EOPD) cases with a known genetic association. More than 100 mutations have been described in the Parkin gene that includes homozygous, compound heterozygous, and single heterozygous mutations. We have designed a Parkin mutation genotyping array (gene chip) that includes published Parkin sequence variants and allows their simultaneous detection. The chip was validated by screening 85 PD cases and 47 controls previously tested for Parkin mutations. Similar genotyping microarrays have been developed for other genetically heterogeneous diseases including age-related macular degeneration. Here, we show the utility of a genotyping array for Parkinson's disease by analysis of 60 subjects from the Genetic Epidemiology of Parkinson Disease (GEPD) study that includes 15 early-onset PD case probands and 45 relatives.  相似文献   
87.
88.
89.
Summary Tumor DNA from 27 patients with treated or untreated transitional cell carcinomas of the urinary tract was screened for genomic alterations of the multidrug resistance genes in order to determine whether structural changes of these genes are important in primary urothelial tumors. None of the tumors showed evidence of amplification or rearrangements of either mdr1 or mdr2. The lack of amplification or rearrangements observed in these tumors suggests that structural alterations of the mdr1 and mdr2 genes are not important mediators of drug resistance in TCC.Supported in part by grant CA-34775 from the National Institutes of Health and by a grant from the Heckscher Foundation for ChildrenDr. Klein is a fellow of the American Cancer Society  相似文献   
90.
The biological and biomechanical properties of normal fibulae, fibulae that had had a sham operation, and both vascularized and non-vascularized autogenous grafts were studied in dogs at three months after the operation. The study was designed to quantify and correlate changes in these properties in orthotopic, stably fixed, weight-bearing grafts and to provide a baseline for additional studies of allografts. The grafts were eight centimeters long and internally fixed. The mechanical properties of the grafts were studied by torsional testing. Metabolic turnover of the grafts was evaluated by preoperative labeling of the dogs with 3H-tetracycline for resorption of bone mineral and with 3H-proline for turnover of collagen. Cortical bone area and porosity were measured. Postoperative formation of bone was evaluated by sequential labeling with fluorochrome. The vascularized grafts resembled the fibulae that had had a sham operation and those that had not had an operation with regard to the total number of osteons and the remodeling process, as measured both morphometrically and metabolically. The vascularized grafts were stronger and stiffer than the non-vascularized grafts and were not different from the bones that had had a sham operation. In contrast, the non-vascularized grafts were smaller, weaker, less stiff, and more porotic, had fewer osteons, and demonstrated increased turnover and resorption compared with the vascularized grafts, the bones that had had a sham operation, and the bones that had not been operated on.  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