全文获取类型
收费全文 | 1472篇 |
免费 | 123篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 138篇 |
妇产科学 | 16篇 |
基础医学 | 211篇 |
口腔科学 | 44篇 |
临床医学 | 190篇 |
内科学 | 216篇 |
皮肤病学 | 19篇 |
神经病学 | 166篇 |
特种医学 | 171篇 |
外科学 | 112篇 |
综合类 | 14篇 |
预防医学 | 60篇 |
眼科学 | 22篇 |
药学 | 121篇 |
中国医学 | 1篇 |
肿瘤学 | 79篇 |
出版年
2021年 | 12篇 |
2020年 | 19篇 |
2019年 | 13篇 |
2018年 | 34篇 |
2017年 | 26篇 |
2016年 | 16篇 |
2015年 | 17篇 |
2014年 | 33篇 |
2013年 | 42篇 |
2012年 | 58篇 |
2011年 | 64篇 |
2010年 | 48篇 |
2009年 | 43篇 |
2008年 | 35篇 |
2007年 | 40篇 |
2006年 | 33篇 |
2005年 | 47篇 |
2004年 | 36篇 |
2003年 | 42篇 |
2002年 | 26篇 |
2001年 | 39篇 |
2000年 | 37篇 |
1999年 | 32篇 |
1998年 | 46篇 |
1997年 | 41篇 |
1996年 | 41篇 |
1995年 | 35篇 |
1994年 | 39篇 |
1993年 | 27篇 |
1992年 | 41篇 |
1991年 | 35篇 |
1990年 | 34篇 |
1989年 | 46篇 |
1988年 | 35篇 |
1987年 | 48篇 |
1986年 | 31篇 |
1985年 | 40篇 |
1984年 | 40篇 |
1983年 | 19篇 |
1982年 | 27篇 |
1981年 | 20篇 |
1980年 | 20篇 |
1979年 | 8篇 |
1978年 | 13篇 |
1977年 | 20篇 |
1976年 | 23篇 |
1975年 | 17篇 |
1974年 | 9篇 |
1973年 | 11篇 |
1969年 | 6篇 |
排序方式: 共有1599条查询结果,搜索用时 15 毫秒
1.
Direct (intraarterial) and two indirect (using a mercury sphygmomanometer [MS] and an automatic [auscultatory] device) methods of blood pressure measurement were compared in intensive care patients (N = 32). One trained observer blind to both automatic and direct measurements obtained all indirect MS measurements. All direct and indirect measurements were made on the same arm. Direct measurements were obtained from 10-second strip chart recordings. In normotensive patients both indirect measurements of systolic blood pressure (SBP) underestimated the direct SBP; however, only the SBP value obtained with the automatic device (106 mm Hg) was significantly different, p less than .05, from the direct SBP value (120 mm Hg). No significant difference was noted between methods in measurement of normotensive diastolic blood pressure. In hypertensive patients direct SBP was significantly greater, p less than .05, from both values obtained by indirect measurement. In patients without hypotension the automatic device may be substituted for the MS and direct blood pressure methods. The automatic device may offer the advantage of decreasing observer bias and variability in blood pressure measurement. 相似文献
2.
P. J. Foreman G. Taglialatela L. Angelucci C. P. Turner J. R. Perez-Polo 《Journal of neuroscience research》1993,36(1):10-18
The synthesis of nerve growth factor (NGF) by the hippocampus raises the possibility that NGF may play a role in the regulation of the hypothalamic-pituitary-adrenal axis (HPAA). Subchronic cold stress has been shown to activate the HPAA in a mild noninvasive manner, to stimulate serum glucocorticoid levels, and to perturb NGF binding in hippocampus and basal forebrain. One or repeated episodes of cold stress increased NGF mRNA levels in the hippocampus and p75NGFR mRNA levels in the basal forebrain. These changes were not due to elevated serum glucocorticoid levels since treatment with exogenous corticosterone had no effect on NGF and p75NGFR mRNA levels. Adrenalectomy did not prevent the stress induced increases in NGF and p75NGFR mRNA. © 1993 Wiley-Liss, Inc. 相似文献
3.
Acute appendicitis: CT and US correlation in 100 patients 总被引:19,自引:1,他引:18
4.
Perforated colorectal neoplasms: correlation of clinical, contrast enema, and CT examinations 总被引:2,自引:0,他引:2
Hulnick DH; Megibow AJ; Balthazar EJ; Gordon RB; Surapenini R; Bosniak MA 《Radiology》1987,164(3):611-615
Results of clinical, contrast enema (CE), and computed tomographic (CT) examinations in 39 patients with perforated colorectal neoplasms were retrospectively reviewed. Twenty patients were toxemic at initial presentation, but in only four patients was the diagnosis of perforated colorectal neoplasm initially suspected clinically. CE study was performed in 22 patients and enabled the diagnosis of perforated neoplasm in 11 cases, neoplasm alone in eight, and neither neoplasm nor perforation in three. CT was performed in 38 patients and enabled the diagnosis of perforated neoplasm in 36; pericolic phlegmon but no mass lesion was evident in two. In 16 patients, CT also demonstrated metastatic disease. Because of its reliability in establishing the diagnosis and staging the extent of the inflammatory and neoplastic disease, CT is indicated in cases of suspected or proved perforated colorectal neoplasm and in cases in which CE study findings are indeterminate or suggestive of perforated neoplasm. 相似文献
5.
6.
K. E. Foreman T. Wrone-Smith L. H. Boise C. B. Thompson P. J. Polverini P. L. Simonian G. Nunez B. J. Nickoloff 《The American journal of pathology》1996,149(3):795-803
Several recently identified proteins such as Bcl-2 and Bcl-x have been found to regulate programmed cell death (i.e., apoptosis). In this report, we examined the levels of expression of proteins that can either prevent apoptosis (i.e., Bcl-2 or the long form of Bcl-x, designated Bcl-x1) or promote apoptosis (i.e., Bax or the short form of Bcl-x, designated Bcl-xs) in proliferating benign and malignant endothelial cells (ECs). In normal skin with quiescent ECs, no detection by immunohistochemical staining was observed for Bcl-xL, Bcl-xs, or Bcl-2. However, in diseased skin samples that feature a prominent angiogenic response such as in psoriasis or pyogenic granulomas, the proliferating ECs markedly overexpressed Bcl-xL, with little to no Bcl-2. In an acquired-immune-deficiency-syndrome-related neoplasm, Kaposi's sarcoma, the spindle-shaped tumor cells also overexpressed Bcl-xL compared with Bcl-2. These in vivo studies were extended in vitro using cultured ECs and Kaposi's sarcoma tumor cells that were examined by flow cytometry and immunoblot analysis. Both cultured ECs and Kaposi's sarcoma tumor cells express significantly higher levels of Bcl-xL than Bcl-2. Such overexpression of cell survival gene products may contribute to prolonging the longevity of EC-derived cells in several different benign and neoplastic skin disorders that are characterized by a prominent angiogenic tissue response. 相似文献
7.
8.
BCSH Blood Transfusion Task Force D. Voak R. Cann R. D. Finney K. Foreman S. M. Knowles R. Mitchell J. A. F. Napier P. K. Phillips A. J. Rejman A. H. Waters J. K. Wood R. M. Hutchinson A. J. Bell J. K. M. Duguid J. M. Hows K. Jestice D. E. Pegg N. G. Testa 《Transfusion medicine (Oxford, England)》1994,4(2):165-172
SUMMARY. There are no current U.K. or international guidelines or regulations covering the production, processing and storage of haemopoietic cells such as to allow their engraftment following myeloablative therapy. This paper seeks to provide such guidelines. It enumerates how quality control and assurance can be applied to this area of transfusion medicine; procedural steps relating to bone marrow harvest on peripheral blood stem cell collection are outlined and recommended doses of nucleated cells suggested for both procedures. General specifications for identification, storage and transportation of bone marrow and peripheral blood stem cells are included and specific laboratory procedures related to the provision of haemopoietic cells for engraftment are outlined. Umbilical cord blood transplants and long-term bone marrow culture are alluded to but these are still in a research phase. 相似文献
9.
10.
Steenbergen EJ; Verhagen OJ; van Leeuwen EF; van den Berg H; von dem Borne AE; van der Schoot CE 《Blood》1995,86(2):692-702
Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL. 相似文献