全文获取类型
收费全文 | 14463篇 |
免费 | 1363篇 |
国内免费 | 78篇 |
专业分类
耳鼻咽喉 | 158篇 |
儿科学 | 454篇 |
妇产科学 | 305篇 |
基础医学 | 1837篇 |
口腔科学 | 293篇 |
临床医学 | 1807篇 |
内科学 | 2903篇 |
皮肤病学 | 228篇 |
神经病学 | 1393篇 |
特种医学 | 646篇 |
外科学 | 2033篇 |
综合类 | 288篇 |
一般理论 | 12篇 |
预防医学 | 1428篇 |
眼科学 | 313篇 |
药学 | 988篇 |
中国医学 | 16篇 |
肿瘤学 | 802篇 |
出版年
2021年 | 222篇 |
2020年 | 130篇 |
2019年 | 217篇 |
2018年 | 267篇 |
2017年 | 216篇 |
2016年 | 238篇 |
2015年 | 244篇 |
2014年 | 321篇 |
2013年 | 502篇 |
2012年 | 666篇 |
2011年 | 682篇 |
2010年 | 375篇 |
2009年 | 408篇 |
2008年 | 617篇 |
2007年 | 703篇 |
2006年 | 728篇 |
2005年 | 634篇 |
2004年 | 607篇 |
2003年 | 530篇 |
2002年 | 507篇 |
2001年 | 493篇 |
2000年 | 481篇 |
1999年 | 412篇 |
1998年 | 172篇 |
1997年 | 174篇 |
1996年 | 142篇 |
1995年 | 148篇 |
1994年 | 126篇 |
1993年 | 121篇 |
1992年 | 282篇 |
1991年 | 295篇 |
1990年 | 333篇 |
1989年 | 294篇 |
1988年 | 241篇 |
1987年 | 240篇 |
1986年 | 250篇 |
1985年 | 225篇 |
1984年 | 202篇 |
1983年 | 162篇 |
1982年 | 123篇 |
1980年 | 109篇 |
1979年 | 153篇 |
1978年 | 129篇 |
1977年 | 122篇 |
1976年 | 135篇 |
1975年 | 100篇 |
1974年 | 127篇 |
1973年 | 99篇 |
1972年 | 119篇 |
1970年 | 103篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
McConaghy (1989) argued that the validity of penile circumference responses (PCRs) is at best unestablished and that penile volume responses (PVRs) have been demonstrated to be clearly superior indices of sexual arousal and orientation. In his critique, McConaghy stated that (i) penile erection has been incorrectly identified with sexual arousal, (ii) that PCRs have not been shown to accurately discriminate between divergent patterns of sexual arousal (including paraphilias), (iii) that the methodologies used to compare the two types of transducers are inappropriate, and (iv) that PCRs should not be used for diagnostic and treatment decisions. In this paper, McConaghy's criticisms are reviewed in the context of the existing literature on the subject. Although PCRs and PVRs involve different methodologies, they generally yield results that bear more similarities than differences. Furthermore, there is an extensive and growing literature on the use of PCR measures with various paraphilias. Several of McConaghy's arguments should be considered tentative while others are clearly unsubstantiated. Most of McConaghy's concerns over the validity and uses of PCR measures are empirical questions. Suggestions for future research are offered. 相似文献
52.
D. Dickerson B. Adams G. Engelbrecht G. Boltman R. Hickman D. Kahn 《Transplant international》1992,5(Z1):S63-S64
The precise cause of allograft dysfunction after renal transplantation often cannot be established by non-invasive means. In clinical practice, radionuclide scans form an integral part of the clinician's armamentarium in the assessment of these patients [1, 2]. Unfortunately, in the clinical setting more than one pathological process may be responsible for the impaired function, making it difficult to correlate the scan appearances with the pathology. In this study in rats we compared the renal DTPA scan appearances of the various pathological processes which may cause renal allograft dysfunction in the immediate post-transplant period. 相似文献
53.
Virgin female BALB/c mice were exposed in vivo to whole body gamma-radiation and/or to 7,12-dimethylbenz[a]anthracene (DMBA) p.o. Mammary epithelial cells were isolated and assayed for carcinogen altered cell populations both in vitro by an epithelial focus assay and in vivo by injection into cleared fat pads of syngeneic host mice. Five groups of mice were exposed as follows: (a) sham controls; (b) 50-rad gamma-radiation; (c) 100-rad gamma-radiation; (d) 75 micrograms DMBA; or (e) 50-rad gamma-radiation followed in 1 week by 75 micrograms DMBA. Mammary epithelial cells were isolated and assayed at 24 h and at 1, 4, 16, and 52 weeks after in vivo exposure. Four to 12 mice per treatment per time point were individually assayed. Altered in vitro growth potential was characterized by the proliferation of carcinogen exposed (but not control) cells as epithelial foci which persisted at least 12 weeks in primary culture. Epithelial foci which could then be subcultured at least four times were termed subculturable epithelial foci. Altered in vivo morphogenic potential was characterized by dysplastic or neoplastic growth in host fat pads. With increased time in situ between exposure and assay, cell populations emerged which exhibited both increased in vitro subculturability and enhanced tumorigenic potential including a host response upon injection in vivo. Further, combined radiation and DMBA resulted in higher frequencies of subculturable epithelial foci than either treatment alone. The relevance of these progressive cellular changes to the process of mammary tumor development is discussed. 相似文献
54.
55.
The purposes of this study were to determine the effects of E. coli endotoxin shock on coronary blood flow (CBF) and myocardial adenine nucleotides and to determine if reactive oxygen species are major causal factors in these effects of endotoxin. Twenty-three pentobarbital-anesthetized Beagle dogs were instrumented for recording cardiorespiratory parameters, injected i.v. with saline (time-matched controls; n = 6) or endotoxin (1.5 mg/kg; n = 17), and studied for 4 h. Endotoxin dogs also received either i.v. saline (shock controls; n = 6) or i.v. treatment with either deferoxamine (30 mg/kg; n = 5) or triple therapy (n = 6) with a combination of allopurinol (150 mg/kg), superoxide dismutase (SOD) (5 mg/kg), and catalase (CAT) (5 mg/kg). Cardiorespiratory and tissue blood flow variables were constant in sham-shock controls during the study, whereas endotoxin dogs developed typical canine endotoxemia with decreased left ventricular (LV) function. CBF was decreased by approximately 40% (P less than or equal to 0.5) in all endotoxin groups throughout the 4 h study period. However, based on hemodynamic estimates of myocardial O2 demand and endocardial/epicardial blood flow ratios, it seemed that coronary flow was matched to metabolic rate in all endotoxin groups. Endotoxin significantly lowered LV myocardial concentrations of ADP, AMP, NADH, and NADPH (range = 37 to 54%, P less than or equal to 0.05), but ATP, NAD, and NADP concentrations were not changed. The adenylate charge of the myocardium was between 0.91 and 0.95 in all endotoxin groups, suggesting that adequate energy was available in the myocardium during endotoxin shock. The lack of influence of deferoxamine, allopurinol, SOD, and CAT is indirect evidence that oxygen radicals are not primary pathophysiologic mediators in the cardiac response to gram-negative endotoxemia in this endotoxin model. 相似文献
56.
Jun Wang Zhong Guo Ying Dong Oliver Kim John Hart rew Adams Christian P. Larsen Robert S. Mittler Kenneth A. Newell 《American journal of transplantation》2003,3(5):543-551
Blockade of traditional costimulatory molecules fails to inhibit rejection in many models where CD8+ T cells are sufficient to mediate rejection. This observation demonstrates that in many settings CD8+ T cells are not dependent upon CD28 or CD154 signals to mediate rejection. 4-1BB (CD137) has been shown to be an important regulatory molecule for CD8+ T cells in a variety of nontransplant models. Here we show that blocking the 4-1BB pathway significantly inhibited rejection of intestinal allografts by CD8+ but not CD4+ T cells. This effect was associated with significantly decreased expression of the genes encoding TNFalpha and secondary lymphoid chemokine (SLC) within the spleens of recipient mice. Disruption of the 4-1BB pathway also impaired the priming of alloantigen-specific CD8+ T cells and the accumulation of recipient dendritic cells within the spleen. These data directly demonstrate an important role for 4-1BB in allograft rejection; particularly rejection mediated by CD8+ T cells. Our data suggest that in addition to providing a direct costimulatory signal to T cells, the 4-1BB pathway may regulate other important steps in the immune response such as the migration of T cells and dendritic cells. 相似文献
57.
缺血性卒中或短暂性脑缺血发作患者的卒中预防指南 总被引:8,自引:0,他引:8
Ralph L.Sacco Robert Adams Grge Albers Mark J.ALBERTS Oscar Benavente Karen Furie Larry B.Goldstein Philip Gorelick Jonathan Halperin Robert Harbaugh S.Claiborne Johnston Irene Katzan Margaret Kelly-Hayes Edgar J.Kenton Michael Marks Lee H.Schwamm Thomas Tomsick 曹勇军 《中华脑血管病论坛》2006,4(1):21-66
这份新声明旨在为缺血性卒中或短暂性脑缺血发作存活者的缺血性卒中预防提供全面和及时的循证推荐,循证推荐包括对危险因素的控制,动脉粥样硬化性疾病的干预措施,心源性栓塞的抗栓治疗以及非心源性卒中抗血小板药的应用。另外,还为其他多种特殊情况下复发性卒中的预防提供了推荐、包括动脉夹层分离、卵圆孔未闭、高同型半胱氨酸血症、高凝状态、镰状细胞病、脑静脉窦血栓形成、女性卒中(特别是与妊娠和绝经后激素替代治疗相关卒中),脑出血后肮凝药的应用,以及该指南在高危人群中执行和应用的特殊措施。 相似文献
58.
P. H. Winocour K. J. Moriarty C. N. Hales J. Adams R. Reeve D. Wynick D. Allison S. R. Bloom D. C. Anderson 《Postgraduate medical journal》1992,68(797):196-200
A 15 year old girl with a family history of type 1 multiple endocrine adenomatosis presented with reversible neurological disturbances, hypoglycaemia and hyperinsulinaemia. Initial radiology was normal, but portal venous sampling suggested an insulinoma in the tail of the pancreas which was removed with conservation of the spleen. Hypoglycaemia persisted despite high doses of diazoxide and intravenous dextrose. A second laparotomy revealed a pancreatic endocrine tumour and sub-total pancreatectomy was performed. Histology revealed islet cell microadenomatosis. Hypoglycaemia persisted despite treatment with somatostatin analogues and 40% intravenous dextrose was required to maintain normoglycaemia. A possible lesion near the splenic hilum on computed tomographic scan was reported as a splenunculus although further peripheral, hepatic and portal venous sampling suggested hepatic or systemic lesions. A positron emission scan and selective visceral angiography suggested a lesion in the left upper quadrant. Acute lactic acidosis, rhabdomyolysis and renal failure supervened. Post mortem revealed the putative ''splenunculus'' to be a residual insulinoma, whilst the splenic vein was thrombosed, accounting in part for discrepant venous sampling data. Hyperinsulinaemia in type 1 multiple endocrine adenomatosis may require more aggressive surgical and hormonal intervention than when dealing with solitary insulinomas. Insulinomas may mimic developmental abnormalities on computed tomographic scanning. 相似文献
59.
The number, size, and location of cerebral infarctions, and blood flow in the middle cerebral artery as seen on proton magnetic resonance imaging were assessed in six white adults with angiographically documented moyamoya. Findings were correlated with clinical presentation, computed tomography, and angiography. Large hemispheric infarctions were found in five hemispheres, predominantly in watershed regions. Subcortical infarctions (n = 56) were found in all hemispheres. They were predominantly located in the centrum semiovale, in the distal beds of supply of the penetrating branches of the anterior and middle cerebral arteries. Infarction of the putamen was found in three hemispheres, caudate nucleus in four, globus pallidus in two, and anterior limb of the internal capsule in two. There were none in the posterior limb of the internal capsule, thalamus, brain stem, or cerebellum. Middle cerebral artery flow was visualized as a signal-void flow sign in only three hemispheres. Cerebral infarctions due to moyamoya are bilateral, multiple, often small, and asymptomatic, affecting predominantly the carotid circulation in watershed regions. Subcortical infarctions in the centrum semiovale and large hemispheric infarctions in hemodynamically compromised areas are the predominant findings. 相似文献
60.
P J Wood I J Stratford J M Sansom B M Cattanach R M Quinney G E Adams 《International journal of radiation oncology, biology, physics》1992,22(3):473-476
31P magnetic resonance spectroscopy has been used to compare the effects of the vasoactive agents hydralazine and flunarizine on the oxygenation of the transplantable tumors, SCCVII/Ha and 16C, and a range of spontaneous mammary tumors arising in the breeding stock in the Genetics Division at the Radiobiology Unit. The vasodilator hydralazine, previously shown to increase the radiobiological hypoxic fraction of transplantable murine tumors, increased inorganic phosphate to total phosphate (Pi/total) in SCCVII/Ha and 16C tumors. However, only two spontaneous tumors responded to this agent (2/12). The calcium antagonist flunarizine, which sensitizes the SCCVII tumor to X rays, consistent with a reduction in hypoxic fraction, reduced Pi/total in this and the 16C tumor. Further, most spontaneous tumors tested (8/10) responded to this agent, as measured by a reduction in Pi/total. These results point to fundamental differences between transplantable and spontaneously arising tumors in mice in their response to vasoactive agents. 相似文献