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   4351篇
  免费   277篇
  国内免费   15篇
耳鼻咽喉   50篇
儿科学   131篇
妇产科学   163篇
基础医学   541篇
口腔科学   79篇
临床医学   444篇
内科学   1033篇
皮肤病学   73篇
神经病学   292篇
特种医学   451篇
外科学   566篇
综合类   88篇
预防医学   315篇
眼科学   31篇
药学   212篇
中国医学   4篇
肿瘤学   170篇
  2021年   38篇
  2020年   38篇
  2019年   49篇
  2018年   55篇
  2017年   55篇
  2016年   48篇
  2015年   64篇
  2014年   90篇
  2013年   124篇
  2012年   145篇
  2011年   171篇
  2010年   106篇
  2009年   84篇
  2008年   134篇
  2007年   185篇
  2006年   183篇
  2005年   175篇
  2004年   201篇
  2003年   170篇
  2002年   179篇
  2001年   162篇
  2000年   198篇
  1999年   157篇
  1998年   66篇
  1997年   54篇
  1996年   68篇
  1995年   44篇
  1994年   49篇
  1993年   39篇
  1992年   99篇
  1991年   88篇
  1990年   96篇
  1989年   68篇
  1988年   63篇
  1987年   79篇
  1986年   60篇
  1985年   75篇
  1984年   53篇
  1983年   48篇
  1982年   32篇
  1981年   30篇
  1979年   50篇
  1978年   36篇
  1977年   35篇
  1976年   30篇
  1974年   34篇
  1973年   33篇
  1971年   39篇
  1968年   28篇
  1967年   29篇
排序方式: 共有4643条查询结果,搜索用时 15 毫秒
991.
992.
Gastric heterotopia of the small intestine is a rare occurrence outside of Meckel's diverticulum and intestinal duplication. The vast majority of cases of gastric heterotopia occur as polypoid or tumorous lesions in the duodenum. These lesions have been associated with clinical symptoms including diarrhea, obstruction, dyspepsia, ulceration, and gastrointestinal bleeding. We present a case of gastric heterotopia that is unique because the lesions occurred as multiple, carpet-like, nonpolypoid areas throughout a large portion of the small intestine. A review of the literature is included. Received March 10, 1999; accepted June 28, 1999.  相似文献   
993.
Dislocations of the carpal bones are common, but dorsal dislocation of the triquetrum is rare and has only recently been reported in the English-language literature. This case report describes such an injury associated with rotary subluxation of the scaphoid that was successfully treated with closed reduction and cast immobilization for 8 weeks.  相似文献   
994.
Methemoglobin levels following intravenous lidocaine administration   总被引:1,自引:0,他引:1  
Methemoglobin levels were obtained before and after administration of IV lidocaine in 40 cardiac patients. Patients were given a 1-mg/kg bolus of IV lidocaine hydrochloride, started on a maintenance infusion at 2.0 mg/min, and given a second bolus of lidocaine of 0.5 mg/kg 15 minutes after the initial bolus. The maintenance infusion was adjusted from 1 to 4 mg/min according to clinical needs. Methemoglobin levels were drawn at zero, one, and six hours, and lidocaine levels were drawn at one and six hours after the initial bolus. Elevation of methemoglobin levels after lidocaine administration was statistically significant (P less than .05), but not clinically significant. The highest methemoglobin level obtained was 1.2%. Only one other patient had a level above 1%. No patient developed either signs of lidocaine toxicity or toxic levels of methemoglobin. Routine determination of methemoglobin levels is not clinically indicated following routine lidocaine administration. It may have some as-yet-undetermined value in lidocaine-toxic patients.  相似文献   
995.
In the present study orthodontic force was applied to the molars of rats treated with the lathyrogen beta-aminopropionitrile (BAPN). New bone formation was measured at two alveolar locations after 9 days of force application. Observation resulted in the following conclusions: 1. New alveolar bone formation in response to orthodontic force in BAPN-treated rats statistically exceeded corresponding bone formation in control animals when measured at two tension sites in the periodontal ligament. 2. BAPN administration produced disorganization of the collagenous fibers of the periodontium of experimental animals. Multiple eosinophilic cell-free areas were found distributed throughout the radicular portions of affected periodontal ligaments. Normal ligament function architecture was disrupted in treated animals. The areas of periodontium surrounding orthodontically treated teeth exhibited relatively normal organization under these conditions, while the periodontium of adjacent nonorthodontically treated teeth was markedly disorganized. Orthodontic stimulation of the periodontium of BAPN-treated rats may have disrupted the formation of eosinophilic cell-free areas characteristically seen in the periodontium of the experimental group. 3. The present results suggest that the typical histologic response to orthodontic force application can occur in the presence of a chemically and physically altered periodontium. The quantitative data collected infer that fiber tension on the alveolus may not be absolutely necessary to stimulate bone formation. Distortion of the alveolus related to force application may be a more important factor initiating bone response. However, the fibers of the periodontium may play a passive role in transferring orthodontic force to the alveolus.  相似文献   
996.
An inbred strain of fawn hooded rats with a congenital platelet defect shows a marked bleeding tendency with prolonged bleeding time. This haemorrhagic disorder has been exclusively related to a deficiency of nucleotides in platelet dense granules. When tested in cell electrophoresis platelets from fawn hooded bleeder rats showed a significantly lower electrophoretic mobility than normal rat platelets. Subsequent studies on the platelet membrane protein pattern by high resolution two-dimensional gel electrophoresis revealed the deficiency of a membrane glycoprotein (apparent molecular mass 90.000, isoelectric point 5.6), which is detectable in normal rat platelets after surface labeling by periodate-tritiated sodium borohydride. It seems likely, that this glycoprotein defect contributes at least partially to the disorder of platelet function in fawn hooded bleeder rats.  相似文献   
997.
To test the hypothesis that patients with normal serum levels of creatine kinase (CK) but elevated percentages of MB isoenzyme fractions in suspected myocardial infarction may have sustained clinically significant events, we studied the hospital course of 347 consecutive patients admitted with suspected myocardial infarction. Two hundred twenty-three patients had normal CK levels (182 +/- 44 IU) and normal MB percentages (normal group), 68 had elevated levels of both CK (1395 +/- 178 IU) and MB percentage (10.5 +/- 0.6) (macroinfarction group), and 40 had normal CK levels (96 +/- 7 IU) but elevated MB percentages (9.6 +/- 0.5) with typical enzyme curves (microinfarction group). Compared to the normal group, microinfarction patients were older, had more congestive heart failure, required more intensive monitoring and therapy during longer stays, and sustained a higher in-hospital mortality rate. Thus, these microinfarction patients are at increased risk and therefore warrant aggressive treatment and further evaluation.  相似文献   
998.
999.
OBJECTIVES: Different aberrations in one chromosome 18 were prenatally detected during each of three different pregnancies of a healthy woman. Routine cytogenetic analysis revealed a morphologically altered maternal chromosome 18 as well. The purpose of the current study was to characterize these cytogenetic changes in detail and thus to clarify the reason for the recurrent appearance of morphologically altered chromosomes 18 in this family. METHODS: As GTG banding did not allow resolution of the kind of aberrations present in these four cases, the following molecular cytogenetic approaches were used: microdissection combined with reverse painting and multicolour banding (MCB) analysis using a chromosome 18 specific probe set. RESULTS: Molecular cytogenetic approaches revealed that fetus 1 had a derivative chromosome del(18)(q11.2q12.2), fetus 2 and the mother had the identical derivative chromosomes ins(18)(pterp11.32::q12.2q11.2::p11.32q11.2::q12.3qter) and fetus 3 had a dup(11.2q12.2). CONCLUSION: Partial monosomy in fetus 1 and partial trisomy in fetus 3 can be explained by crossing over events during maternal meiosis.  相似文献   
1000.
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