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   2278篇
  免费   99篇
  国内免费   11篇
耳鼻咽喉   7篇
儿科学   39篇
妇产科学   38篇
基础医学   254篇
口腔科学   38篇
临床医学   110篇
内科学   431篇
皮肤病学   12篇
神经病学   241篇
特种医学   164篇
外科学   490篇
综合类   1篇
预防医学   51篇
眼科学   34篇
药学   172篇
中国医学   1篇
肿瘤学   305篇
  2022年   17篇
  2021年   21篇
  2019年   12篇
  2018年   37篇
  2017年   28篇
  2016年   32篇
  2015年   22篇
  2014年   48篇
  2013年   61篇
  2012年   77篇
  2011年   118篇
  2010年   61篇
  2009年   45篇
  2008年   100篇
  2007年   121篇
  2006年   110篇
  2005年   118篇
  2004年   150篇
  2003年   149篇
  2002年   154篇
  2001年   62篇
  2000年   63篇
  1999年   55篇
  1998年   40篇
  1997年   31篇
  1996年   35篇
  1995年   28篇
  1994年   31篇
  1993年   19篇
  1992年   50篇
  1991年   54篇
  1990年   43篇
  1989年   35篇
  1988年   27篇
  1987年   29篇
  1986年   28篇
  1985年   23篇
  1984年   21篇
  1983年   11篇
  1980年   15篇
  1979年   19篇
  1978年   14篇
  1976年   10篇
  1974年   16篇
  1973年   11篇
  1972年   15篇
  1971年   11篇
  1970年   11篇
  1969年   15篇
  1966年   10篇
排序方式: 共有2388条查询结果,搜索用时 0 毫秒
11.
We report on a 19-month-old girl with a derivative chromosome 9 and a recombinant chromosome 12 resulting from a maternal balanced complex rearrangement involving chromosomes 8, 9, and 12. The karyotype of the phenotypically normal mother was 46,XX,t(8;12) (9;12) (8qter→8p23::12q12→12q15::9q32→9qter;9pter→9q32::12q15→12qter;12pter→12q12::8p23→8pter). The child's karyotype was 46,XX,?9,?12, +der(9) (9pter→9q32::12q15→12qter),+rec(12) (12pter→12q15::9q32→9qter) mat. The child had severe growth retardation, minor anomalies including trigonocephaly, hypertelorism, broad nasal root, apparently low-set and posteriorly angulated ears, triangular face, pectus carinatum, clinodactyly of fifth fingers, and almost normal psychomotor development. To the best of our knowledge, there have been only 3 previous reports of recombination derived from parental complex chromosome rearrangements. In the recombination products, the chromosomes were apparently balanced and the offspring had no clinical abnormalities. The present case exhibited abnormalities and may have a submicroscopic aberration of 12q arising from crossing over during maternal meiotic pairing, although her chromosomes appeared to be balanced. © 1993 Wiley-Liss, Inc.  相似文献   
12.
A DNA hybridization method with an enzyme-labeled oligonucleotide probe (mecA-ELONP) was developed to detect the methicillin-resistant gene (mecA) in methicillin-resistant Staphylococcus aureus. For rapid identification, bacterial colonies were transferred from agar plates directly onto nylon membranes. Lysis of cells, denaturation of DNA, and hybridization were performed on the membranes. These procedures required only 3 h for completion. The results obtained by this test closely corresponded with those obtained by determining the MICs of oxacillin against S. aureus. The results of the mecA-ELONP also correlated well with those of a commercially available PCR test. Thus, mecA-ELONP proved to be a reliable and convenient method for the rapid identification of methicillin-resistant S. aureus, which could be useful in clinical microbiology laboratories.  相似文献   
13.
A case of mixed medullary follicular carcinoma of the thyroid is reported. Grossly, the tumor was a solid, grayish white, well circumscribed mass without lymph node metastasis. Microscopically, the tumor showed both medullary and follicular areas. The follicular areas occupied discrete portions of the tumor, and were considered to be neoplastic. Tumor cells in the medullary area were polyhedral or spindle-shaped. There was no amyloid deposition within the tumor. Immunohistochemically, tumor cells in the medullary area were positive for calcitonin and negative for thyroglobulin. Some cells lining the follicles were positive for thyroglobulin. By electron microscopy, two types of tumor cell were observed. One type contained numerous cytoplasmic secretory granules, whereas the other type had few granules and showed a prominent rough endoplasmic reticulum. These findings suggested that this mixed medullary follicular carcinoma of the thyroid presented neoplastic changes within a common cell lineage.  相似文献   
14.
15.
I-J as an Inducible T Cell Receptor for Self   总被引:4,自引:0,他引:4  
"Jedenfalls, wenn man davorsteht, dann sieht man sich selbstaber eben nicht wie in einem gewöhnlichen Spiegel, versteht sich. Man sieht nicht sein Äusseres, sondern man sieht sein wahres inneres Wesen. so wie es in Wirklichkeit beschaffen ist. Wer da durch will, der muß - um es mal so auszudrücken -in sich selbst hineingehen."
Die undendliche Geschichte, bei Michael Ende, K. Thiehemanns Verlag, Stuttgart, 1979.  相似文献   
16.
The evolutionally conserved Cdc7 kinase plays crucial roles in initiation of DNA replication as well as in other chromosomal events. To examine the roles of Cdc7 in brain development, we have generated mice carrying Cdc7 knockout in neural stem cells by using Nestin-Cre. The Cdc7Fl/Fl NestinCre mice were born, but exhibited severe growth retardation and impaired postnatal brain development. These mice exhibited motor dysfunction within 9 days after birth and did not survive for more than 19 days. The cerebral cortical layer formation was impaired, although the cortical cell numbers were not altered in the mutant. In the cerebellum undergoing hypoplasia, granule cells (CGC) decreased in number in Cdc7Fl/F lNestinCre mice compared to the control at E15-18, suggesting that Cdc7 is required for DNA replication and cell proliferation of CGC at mid embryonic stage (before embryonic day 15). On the other hand, the Purkinje cell numbers were not altered but its layer formation was impaired in the mutant. These results indicate differential roles of Cdc7 in DNA replication/cell proliferation in brain. Furthermore, the defects of layer formation suggest a possibility that Cdc7 may play an additional role in cell migration during neural development.  相似文献   
17.
Since its conception, several techniques have been described for laparoscopic appendicectomy. We describe a technique which utilizes a 5-mm bipolar forceps designed to coagulate and cut tissues at the same time; 50 pediatric patients underwent laparoscopic appendicectomy for acute appendicitis using this stripping and teasing technique. No bleeding complications occurred. There were only two postoperative abscesses in the series. We believe that the bipolar laparoscopic striptease appendicectomy technique as developed by the senior author is safe, quick, and effective, even for severe appendicitis.  相似文献   
18.
Twelve patients with jugular foramen neurinoma were operated on at our clinic between 1974 and 1990. The initial signs and symptoms were variable; dysfunctions of the 7th, 8th, 9th, 10th, and 11th nerves were frequently observed. Among these, involvement of the eighth nerve was most frequent, and three patients were given a misdiagnosis of acoustic neurinoma. Computed tomography scan and magnetic resonance imaging were useful not only for the correct diagnosis, but also for planning the surgical treatment and postoperative followup. Surgical resection was accomplished with four different approaches: (1) suboccipital approach without opening the jugular foramen, (2) suboccipital approach with opening the jugular foramen, (3) suboccipital approach with opening the jugular foramen combined with infralabyrinthine approach, (4) infralabyrinthine approach. The surgical approach depended on the presence of intracranial tumor and on the extent of extracranial involvement. There was no operative mortality. Dysfunction of the 8th, 9th, 10th, or 11th nerve did not improve in any patient after tumor removal. In contrast, 12th nerve palsy improved in two of three patients after tumor removal. The nerve of origin was identified in five cases; those were from the ninth nerve in three and from the 11th nerve in two.  相似文献   
19.
A 72-year-old Japanese woman, suffering from squamous cell lung cancer with brain metastasis, underwent 2 courses of combination chemotherapy, consisting of cisplatin and vindesine. Although both the primary tumor and the brain metastasis regressed markedly, she developed left ocular pain with blurred vision. An abnormal mass was found in the left iris, and cytologic examination of the aqueous aspirate revealed a few malignant cells, which, when examined by electron microscopy, were considered to be derived from squamous cell carcinoma of the lung.  相似文献   
20.
We have examined the suppressive effect of herbimycin A on the reduction of gap-junctional Intercellular communication that is induced by a tumor-promoting phorbol ester in 3T3-L1 cells. Most cells in growth arrest participated in dye-coupling, as evaluated by the transfer between cells of a fluorescent dye (Lucifer Yellow CH). Treatment of cells with 0.25 μg/ml herbimycin A slightly enhanced the dye-coupling. This enhancement required treatment for periods as long as 24 h. Addition of 100 ng/ml 12-O-tetradecanoylphorbol-13-acetate (TPA) caused a rapid reduction of dye-coupling. However, addition of TPA did not suppress dye-coupling in cells pretreated for more than 24 h with herbimycin A. Pretreatment of cells for less than 6 h with herbimycin A did not suppress the TPA-induced reduction of dye-coupling. These results suggest that herbimycin A suppresses the reduction of gap-junctional intercellular communication that is induced by TPA through enhancement of the ability of the cells to participate in gap-junctional intercellular communication  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