全文获取类型
收费全文 | 23996篇 |
免费 | 2241篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 202篇 |
儿科学 | 870篇 |
妇产科学 | 531篇 |
基础医学 | 3119篇 |
口腔科学 | 479篇 |
临床医学 | 2693篇 |
内科学 | 4981篇 |
皮肤病学 | 191篇 |
神经病学 | 2335篇 |
特种医学 | 826篇 |
外科学 | 3346篇 |
综合类 | 412篇 |
一般理论 | 13篇 |
预防医学 | 2740篇 |
眼科学 | 494篇 |
药学 | 1586篇 |
中国医学 | 43篇 |
肿瘤学 | 1423篇 |
出版年
2022年 | 163篇 |
2021年 | 393篇 |
2020年 | 226篇 |
2019年 | 428篇 |
2018年 | 444篇 |
2017年 | 294篇 |
2016年 | 360篇 |
2015年 | 378篇 |
2014年 | 615篇 |
2013年 | 945篇 |
2012年 | 1321篇 |
2011年 | 1332篇 |
2010年 | 740篇 |
2009年 | 650篇 |
2008年 | 1204篇 |
2007年 | 1318篇 |
2006年 | 1231篇 |
2005年 | 1185篇 |
2004年 | 1156篇 |
2003年 | 1134篇 |
2002年 | 1117篇 |
2001年 | 542篇 |
2000年 | 549篇 |
1999年 | 491篇 |
1998年 | 276篇 |
1997年 | 235篇 |
1996年 | 248篇 |
1995年 | 245篇 |
1994年 | 236篇 |
1993年 | 230篇 |
1992年 | 403篇 |
1991年 | 333篇 |
1990年 | 356篇 |
1989年 | 377篇 |
1988年 | 300篇 |
1987年 | 315篇 |
1986年 | 322篇 |
1985年 | 306篇 |
1984年 | 266篇 |
1983年 | 250篇 |
1982年 | 198篇 |
1981年 | 210篇 |
1980年 | 168篇 |
1979年 | 240篇 |
1978年 | 193篇 |
1977年 | 144篇 |
1976年 | 151篇 |
1975年 | 143篇 |
1974年 | 159篇 |
1973年 | 149篇 |
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
91.
Wing-Yen Wong Donald Williams Marilyn L. Slovak Bishan Charak Amitabha Mazumder David Snyder Darleen R. Powars Russell K. Brynes 《American journal of hematology》1993,43(2):133-138
Congenital agranulocytosis terminating in acute myelogenous leukemia has been previously reported in only two cases of adolescent males. We describe the clinical and laboratory features of a 13-year-old male with congenital agranulocytosis, treated with G-CSF with initial good neutrophil response, who subsequently developed acute myeloid leukemia. This rare complication may define a preleukemic subset of patients for whom G-CSF therapy is ineffective. The diagnostic challenges of this case are presented. 相似文献
92.
Cellular blue nevus ("melanocytoma") of the spinal meninges: electron microscopic and immunohistochemical features 总被引:2,自引:0,他引:2
A primary cellular blue nevus (melanocytoma) of the spinal canal in a 21-year-old woman is reported. Light microscopic examination revealed a melanotic neoplasm with histological patterns resembling schwannoma, dermal nevi, and neuroblastic-like tumor. The ultrastructural features of the neoplastic cells were similar to those in dermal blue nevi and melanomas. There was no evidence of arachnoidal cell differentiation. Immunohistochemistry revealed positive reactions for S-100 protein and neuron-specific enolase in many cells and no reactions for glial fibrillary acidic protein, cytokeratins, epithelial membrane antigen, 70-kD neurofilament protein, or Leu-7. Vimentin was strongly positive in the melanocytic cells as well as in the arachnoidal cells of involved meninges. The ultrastructural and immunohistochemical features support the nevoid nature of this tumor, which is frequently mislabeled as "melanotic meningioma." 相似文献
93.
B D Beitman I M Basha L H Trombka M A Jayaratna B D Russell S K Tarr 《Journal of clinical psychopharmacology》1988,8(2):127-130
Ten cardiology chest pain patients without clinical evidence of coronary artery disease and with panic disorder were enrolled in an open label trial of alprazolam. Two dropped out at week 3 because of excessive side effects. The eight study completers showed significant decreases in both Hamilton Anxiety and Hamilton Depression scales by week 2 that remained significant by week 8. On the physician's global impression of change since baseline, all completers were rated at least "much improved." Seven experienced a 50% or greater reduction in panic frequency at week 8 compared to baseline. These results suggest that alprazolam is likely to be of benefit to this patient population. 相似文献
94.
Aircraft disinsection with aerosol insecticides during flight has generally been held to be inadvisable because it was assumed that the insecticides would be rapidly removed by the cabin air-conditioning system. We have developed protocols to deliver 2% d-phenothrin at a dose of 35 g per 100 m3 in various aircraft, and trials undertaken on Boeing 747 and 767 aircraft showed that their air-conditioning systems do not preclude effective disinsection. Mortality levels of 100% for Culex quinquefasciatus and Musca domestica test insects were recorded under normal operating conditions during routine scheduled passenger flights with disinsection procedures undertaken at "blocks-away" or at "top-of-descent". As a result, "top-of-descent" disinsection has been introduced as the recommended procedure for aircraft landing in Australia. 相似文献
95.
J J Tjandra I S Russell J P Collins J T Andrews M Lichtenstein D Binns I F McKenzie 《Cancer research》1989,49(6):1600-1608
The presence of metastases in the regional lymph nodes is the major prognostic factor in breast cancer in the absence of overt distant metastases and is also an important indicator of the need for adjuvant therapy in "early" breast cancer. Currently, the accurate assessment of axillary lymph node status requires axillary dissection which has an associated morbidity. An alternative method of identifying patients who are "node positive" has been developed by means of immunolymphoscintigraphy with s.c. administered radioiodinated monoclonal antibody. The 131I-labeled anti-breast cancer antibody (RCC-1; 400 micrograms) and cold iodine-labeled "blocking" antibody (Ly-2.1; 2 mg which is nonreactive with breast cancer) were injected s.c. into both arms and scintigraphy images were obtained 16-18 h after the injection, using the axilla contralateral to the side of the breast cancer as the control. Studies were reported as positive (and therefore indicative of lymph node metastases) if the amount of background-subtracted radioactive count in the axilla of interest exceeded the normal side by a radio equal to or greater than 1.5:1.0 as assessed by computer analysis. In 38 of 40 patients the findings on scintigraphy were correlated with operative and histopathological findings on the axillary dissection specimen or cytological findings of fine needle aspiration of axillary lymph nodes. In a prospective study of 26 patients, the method is more sensitive (86%) and specific (92%) than preoperative clinical assessment (57% sensitivity, 58% specificity) in the detection of axillary lymph node metastases; and by combining both modalities of assessment, there was an improvement in the sensitivity (100%) but a deterioration in the specificity (50%). There was no significant complication from this essentially outpatient procedure and only 1 of 40 patients developed a human anti-mouse antibody response. This novel and safe method of imaging may become a most useful adjunct in the surgical management of breast cancer. 相似文献
96.
Matched controls in surveys of the use of general practice: Another use for research practice age-sex registers 下载免费PDF全文
Ian Russell 《The British journal of general practice》1975,25(160):801-810
This paper describes how an age-sex register may be used as a sampling frame for the selection of matched controls in studies of the use of general practice. It discusses both the analysis of data collected in this way and the advantages and limitations of the method itself. The application of the method to a case-study suggests that patients who use hospital accident departments are also high users of general practice. Although care is needed in the interpretation of such results, it is concluded that matched controls can be used to ameliorate some of the problems of research in general practice. 相似文献
97.
Benoit SC Air EL Wilmer K Messerschmidt P Hodge KM Jones MB Eckstein DM McOsker CC Seeley RJ Woods SC Sheldon RJ 《Physiology & behavior》2003,79(4-5):761-766
The conditioned taste aversion (CTA) is routinely used to assess the aversive consequences of anorexic agents, including potential pharmacological therapies for obesity. In a typical CTA paradigm, rats briefly sampling a novel tastant (e.g., saccharin) are acutely administered with toxin (e.g., lithium chloride, LiCl). After as few as one taste-toxin pairing, rats will reliably avoid the novel tastant. This paradigm is frequently used for the assessment of possible aversive consequences of drugs that are candidates for pharmacological therapies. The degree to which the drug supports development of a CTA is interpreted as an index of its aversive properties. Difficulties with previous work include the inability to assess affects on food intake and CTA simultaneously, particularly during chronic drug administration. We report here two novel CTA paradigms for the assessment of appetitive and aversive consequences of anorexic agents, simultaneously. In the first experiment, animals receive an intraoral infusion of a novel and highly palatable tastant immediately prior to administration of increasing doses of LiCl. In the second experiment, rats were implanted intraperitoneally with osmotic minipumps that chronically delivered a low dose of LiCl for 7 days. LiCl did not affect short or long term food intake in either experiment. However, LiCl did support the development of a CTA in both paradigms. These results suggest that both the appetitive and aversive consequences of anorexic agents can be assessed simultaneously during either acute or chronic drug administration. 相似文献
98.
Oxidative capacity interacts with oxygen delivery to determine maximal O2 uptake in rat skeletal muscles in situ 总被引:2,自引:1,他引:2
When intracellular recordings were made from the antral region of murine stomach, cells with three different patterns of electrical activity were detected. One group of cells generated follower potentials, the second group generated pacemaker potentials and the third group generated slow waves that consisted of primary and secondary components. Slow waves recorded in different regions of the gastric antrum had similar amplitudes but different characteristic shapes. At the greater curvature, slow waves had large initial components. Midway between the greater and lesser curvature, the amplitude of the initial component was reduced and at the lesser curvature an initial component was difficult to detect. When the distributions of myenteric (ICC-MY) and intramuscular interstitial cells of Cajal (ICC-IM) were determined, using an antibody to Kit, ICC-MY were found to be present at the greater curvature but were greatly reduced in density at the lesser curvature. In contrast, ICC-IM were found in the circular layer of each region. When recordings were made from the antrum of W/WV mice, which lack ICC-IM, incomplete slow waves were detected and their amplitudes fell from the greater to the lesser curvature. Again, a corresponding fall in the density of ICC-MY was detected. The observations indicate that the contribution of ICC-MY and ICC-IM to the generation of slow waves varies in different regions of the mouse gastric antrum. 相似文献
99.
Gregg D. Phillips Russell A. Whitehead David R. Knighton 《Developmental dynamics》1991,192(3):257-262
The object of this study was to examine the initiation and pattern of capillary growth associated with wound healing. Collagen sponges were implanted subcutaneously in the hind limbs of adult male rats to stimulate the formation of granulation tissue. Blood vessels of the hind limbs of euthanized rats were perfused with Mercox (an acrylic monomer) via the abdominal aorta at selected periods of time following sponge implantation. When the perfusate was completely cured, the sponge and parajacent tissues were excised and subsequently macerated by alternating immersion in 40% KOH and distilled water. Cast replicas of the vascular lumina were coated with gold and imaged by scanning electron microscopy. At 6 hr, punctate depressions at the periphery of the replicas of vein and venule lumina were noted. The depressions represented sites of leukocyte margination. By 24 hr, the depressions increased numerically, indicating a great increase in the sites of leukocyte margination. The number of these depressions decreased by 48 hr. Concomitantly, the depressions representing endothelial cell nuclei became more pronounced, indicating nuclear hypertrophy of these cells. In addition, capillary bud formation was initiated. At 72 hr, capillary buds were quite apparent and arose solely from venules. Between 7 and 14 days, replicas of capillary lumina were longer and formed an elaborate network, presumably by end-to-end, side-to-side, and end-to-side anastomoses. The network was formed circumferential to the sponge and then capillary sprouts entered the sponge's interstitial spaces. 相似文献
100.
Prerequisites for translating intervention research findings into practice are maintenance of results, generalization of effects and consistency of implementation. This report presents 12 months follow-up information on a randomized 2x2 factorial trial evaluating the incremental effects of adding (1) telephone follow-up or (2) a community resources utilization component to a basic touchscreen computer-assisted dietary goal-setting intervention for 320 type 2 diabetes patients. All conditions evidenced significant improvement from baseline to the 12 months follow-up across behavioral, biological and psychosocial measures. There were few consistent differences between conditions, but results were robust across interventionists and clinics. The telephone follow-up component appeared to enhance long-term results on some measures. When considered along with earlier results from a randomized trial that included a control condition without goal setting, it is concluded that this basic goal-setting intervention can be consistently implemented by a variety of interventionists and produce lasting improvements. 相似文献