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   8229篇
  免费   582篇
  国内免费   25篇
耳鼻咽喉   70篇
儿科学   425篇
妇产科学   248篇
基础医学   876篇
口腔科学   215篇
临床医学   690篇
内科学   1450篇
皮肤病学   89篇
神经病学   479篇
特种医学   898篇
外科学   1381篇
综合类   114篇
一般理论   7篇
预防医学   598篇
眼科学   587篇
药学   240篇
中国医学   3篇
肿瘤学   466篇
  2021年   84篇
  2018年   115篇
  2017年   80篇
  2016年   86篇
  2015年   106篇
  2014年   123篇
  2013年   222篇
  2012年   257篇
  2011年   302篇
  2010年   226篇
  2009年   186篇
  2008年   322篇
  2007年   275篇
  2006年   280篇
  2005年   242篇
  2004年   248篇
  2003年   242篇
  2002年   226篇
  2001年   216篇
  2000年   209篇
  1999年   230篇
  1998年   203篇
  1997年   180篇
  1996年   178篇
  1995年   149篇
  1994年   127篇
  1993年   134篇
  1992年   179篇
  1991年   189篇
  1990年   196篇
  1989年   255篇
  1988年   212篇
  1987年   229篇
  1986年   207篇
  1985年   209篇
  1984年   179篇
  1983年   161篇
  1982年   96篇
  1981年   72篇
  1980年   103篇
  1979年   122篇
  1978年   113篇
  1977年   94篇
  1976年   109篇
  1975年   91篇
  1974年   92篇
  1973年   92篇
  1972年   67篇
  1971年   75篇
  1970年   59篇
排序方式: 共有8836条查询结果,搜索用时 31 毫秒
101.
The aims of this work were to measure the accuracy of one continuous speech recognition product and dependence on the speaker's gender and status as a native or nonnative English speaker, and evaluate the product's potential for routine use in transcribing radiology reports. IBM MedSpeak/Radiology software, version 1.1 was evaluated by 6 speakers. Two were nonnative English speakers, and 3 were men. Each speaker dictated a set of 12 reports. The reports included neurologic and body imaging examinations performed with 6 different modalities. The dictated and original report texts were compared, and error rates for overall, significant, and subtle significant errors were computed. Error rate dependence on modality, native English speaker status, and gender were evaluated by performing ttests. The overall error rate was 10.3 +/- 3.3%. No difference in accuracy between men and women was found; however, significant differences were seen for overall and significant errors when comparing native and nonnative English speakers (P = .009 and P = .008, respectively). The speech recognition software is approximately 90% accurate, and while practical implementation issues (rather than accuracy) currently limit routine use of this product throughout a radiology practice, application in niche areas such as the emergency room currently is being pursued. This methodology provides a convenient way to compare the initial accuracy of different speech recognition products, and changes in accuracy over time, in a detailed and sensitive manner.  相似文献   
102.
D M Kaufman 《Psychosomatics》1989,30(3):263-269
The face is prominently or exclusively involved in several involuntary movement disorders, called "facial dyskinesias," in addition to the common buccolingual form of tardive dyskinesia. This review describes the appearance of the most frequently occurring facial dyskinesias: chorea, dystonia, tremor, and tics. Some new treatments are discussed.  相似文献   
103.
In experiments on rats the ultrastructure of the muscle tissue of the inferior vena cava after disturbance of the outflow of blood, of the muscular coat of the stomach after resection of 50% of its fundus, and of the muscular coat of the cecum after constriction of its ascending portion was studied. Activation of smooth muscles was shown to reflect the phase of injury to the ultrastructure of the cells, followed by processes of intracellular regeneration. Analysis of the ratio between DNA-synthesizing and activated cells showed the local origin of the latter from differentiated myocytes.Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR. No. 4 Main Board, Ministry of Health of the USSR. Institute of Human Morphology, Academy of Medical Sciences of the USSR. Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 7, pp. 112–115, July, 1977.  相似文献   
104.
Lesions of the articular surfaces of the knee have been managed by various techniques over the last 50 years. Surgical management has involved: excising the damaged area, refashioning the underlying bone to produce a fibrous response, and introducing allograft, autograft and synthetic materials to encourage a repair matrix. The techniques and their pitfalls are reviewed and discussed, and suggestions made as to the direction of future studies for the repair of osteochondral lesions in the painful knee.  相似文献   
105.
Immunopathophysiological mechanisms in endometriosis-associated reproductive failure were studied in appropriate populations: infertile and fertile women with and without endometriosis. The incidence of sera positive for any of the autoantibodies tested among infertile women with endometriosis (n = 25) was similar to that observed in the three control groups [unexplained infertility patients (n = 25) and fertile women with (n = 10) and without (n = 25) endometriosis]. The mean volume of peritoneal fluid was significantly elevated in women with endometriosis (both fertile and infertile) as compared with patients without endometriosis (fertile or infertile). The concentration of peritoneal fluid leukocytes and the percentage of cells positive for macrophage markers were significantly increased and the percentage of T lymphocytes significantly decreased in infertile women with endometriosis but not in patients with unexplained infertility and fertile women with endometriosis, as compared with fertile controls without endometriosis. Macrophages from infertile patients with endometriosis had higher sperm phagocytosis than did those from infertile women without endometriosis or fertile subjects with or without endometriosis. Incidences of serum and peritoneal fluid samples embryotoxic to the in-vitro development of 2-cell mouse embryos were significantly higher in infertile patients with endometriosis than in unexplained infertility patients and fertile women with or without endometriosis. It is concluded that immunological mechanisms of endometriosis-associated infertility exist but that these peritoneal immunological factors in infertile women with endometriosis are related to their subfertility rather than to the presence of ectopic endometrial implants. This is supported by the lack of immunological abnormalities observed among fertile women with endometriosis. These immunological abnormalities are lacking in patients with unexplained infertility.   相似文献   
106.
Highly specific antibodies bound to carcinogen adducts in DNAmodified with (+ / - )7ß, 8-dihydroxy-9, 10-epoxy-7,8, 9, 10-tetrahydrobenzo[a]pyrene (BPDE I) were quantitatedby electron microscopy (EM) visualization and these observationswere compared with quantitation of adducts by enzyme-linkedimmunosorbent assay (ELISA). The antiserum, elicited in rabbitsfollowing inoculation with BPDE I-modified DNA, has been foundto be highly specific in its recognition of BPDE I-deoxyguanosinemoieties. Parallel DNA samples prepared for analysis by ELISAand EM quantitation were randomized, encoded, and analyzed todetermine extents of carcinogen modification in double-blindstudies. After levels of modification were determined by immunoassays,DNA samples were prepared for EM analysis by incubation withamounts of anti-BPdG-DNA serum in excess of that necessary forcomplete binding of antibody to antigenic sites. At equilibrium,samples were enzymatically digested with papain in order tocleave anti-BPdG-DNA IgG molecules into Fab fragments in situ.Following column exclusion chromatography, BPdG-DNA-Fab complexeswere incubated with ferritin-labeled Fab‘ fragments ofgoat [anti-rabbit F(ab’)2] IgG in amounts in excess ofthose necessary for complete binding. When DNA samples weremodified to between 0 and 40 fmol adduct/ µg DNA, excellentagreement was obtained between ELISA quantitation and visualizationby EM of antibodies bound to adducts.  相似文献   
107.
When a focused carbon dioxide laser beam strikes a surface of tissue, the light energy is converted instantly into thermal energy, causing cells directly in the laser's path to vaporize. Because the carbon dioxide laser's energy is well absorbed by water, this thermal effect is attenuated at a distance of 100 mu. If the laser beam is "defocused," the same thermal energy is dissipated over a larger area, causing only desiccation and melting of tissue without vaporization; however, the depth of injury remains shallow. This modified technique has been used to seal artificially created air leaks in the canine lung. Twelve mongrel dogs were anesthetized, intubated, and ventilated. The lingula was exposed sterilely through a left thoracotomy. A 1 X 3-mm hole was made in the lung at 1 cm from the edge. The created air and blood leaks were sealed with a defocused carbon dioxide laser beam set at 8 W (32 W/sq cm). Each tissue "weld" withstood 40 cm H2O of peak ventilation pressure without leak. At the time of reoperation three weeks later, there was apparent complete healing of the pulmonary surface. No air leaks were present. Histologic examination showed a small zone of amorphous coagulated pleura and lung overlying a zone of minimal atelectasis. Normal lung was present within 150 mu of the laser seal. This new technique was performed safely and easily with currently available carbon dioxide lasers in the laboratory. It is presently undergoing intraoperative trials in a controlled clinical setting.  相似文献   
108.
The ileoanal J pouch: radiographic evaluation   总被引:1,自引:0,他引:1  
Hillard  AE; Mann  FA; Becker  JM; Nelson  JA 《Radiology》1985,155(3):591-594
Endorectal ileoanal pull-through offers an attractive alternative to proctocolectomy and ileostomy for patients with ulcerative colitis, Gardner syndrome, and familial polyposis. To our knowledge, a careful radiographic analysis of the ileum, ileal pouch, and ileoanal anastomosis after ileoanal pull-through has not been reported. Thirty-two patients with ulcerative colitis, Gardner syndrome, and familial polyposis underwent colectomy, mucosal proctectomy, and endorectal ileoanal pull-through of a 15-cm ileal "J" pouch and loop ileostomy. Twenty-five (78%) of 32 of all the pouches radiographically demonstrated spiral folds extending from the middle of the pouch to the pectinate line. Other radiographic features included a mesenteric mass effect, pseudopolyps, and a central lucency that indicated intrapouch sutures. Radiographs provide useful information in the postoperative management of the ileal pull-through.  相似文献   
109.
Summary High spinal (cervical and upper thoracic) dysrhaphism usually involves either a meningocele or a dermal sinus tract. These high spinal lesions can have a complex intradural anatomy at the level of the lesion (as this case reports) and are associated with an increased incidence of lower spinal occult dysrhaphic anomalies. It is therefore recommended that patients with high spinal dysrhaphism undergo radiological evaluation of the entire spine to identify those patients with intradural anomalies, define the anatomy for surgery, and investigate the lower spine for associated occult anomalies.  相似文献   
110.
Although the objective of this article was to discuss the specific medically treatable causes of male infertility, the reader will be impressed by the fact that many of the treatments seem less than "specific." The need to treat infections to improve fertility is ill defined. The utilization of a scrotal cooling device as "specific" nonsurgical treatment for varicocele is yet to be defined. Immunologic suppression is indeed a specific form of therapy for a measurable phenomenon; unfortunately, the significance of that phenomenon as well as the best means and location of its assessment are undergoing significant reevaluation. An exciting frontier is the prospect of preventing infertility in the patient undergoing therapy for cancer, thus obviating the need for treatment of the ensuing infertility. Before specific therapies can be anticipated to have a predictable beneficial effect, these areas require active investigation to define the problem more clearly.  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