全文获取类型
收费全文 | 38722篇 |
免费 | 2848篇 |
国内免费 | 486篇 |
专业分类
耳鼻咽喉 | 736篇 |
儿科学 | 749篇 |
妇产科学 | 851篇 |
基础医学 | 5597篇 |
口腔科学 | 651篇 |
临床医学 | 3319篇 |
内科学 | 8628篇 |
皮肤病学 | 1011篇 |
神经病学 | 2863篇 |
特种医学 | 1880篇 |
外科学 | 5279篇 |
综合类 | 645篇 |
一般理论 | 18篇 |
预防医学 | 1814篇 |
眼科学 | 1201篇 |
药学 | 3194篇 |
中国医学 | 351篇 |
肿瘤学 | 3269篇 |
出版年
2023年 | 246篇 |
2022年 | 641篇 |
2021年 | 1139篇 |
2020年 | 594篇 |
2019年 | 966篇 |
2018年 | 1099篇 |
2017年 | 796篇 |
2016年 | 1040篇 |
2015年 | 1386篇 |
2014年 | 1670篇 |
2013年 | 1940篇 |
2012年 | 2863篇 |
2011年 | 3012篇 |
2010年 | 1792篇 |
2009年 | 1527篇 |
2008年 | 2300篇 |
2007年 | 2279篇 |
2006年 | 2048篇 |
2005年 | 1945篇 |
2004年 | 1745篇 |
2003年 | 1618篇 |
2002年 | 1480篇 |
2001年 | 802篇 |
2000年 | 725篇 |
1999年 | 691篇 |
1998年 | 334篇 |
1997年 | 291篇 |
1996年 | 258篇 |
1995年 | 226篇 |
1994年 | 214篇 |
1993年 | 147篇 |
1992年 | 342篇 |
1991年 | 262篇 |
1990年 | 286篇 |
1989年 | 282篇 |
1988年 | 270篇 |
1987年 | 228篇 |
1986年 | 209篇 |
1985年 | 197篇 |
1984年 | 167篇 |
1983年 | 152篇 |
1982年 | 133篇 |
1981年 | 131篇 |
1980年 | 118篇 |
1979年 | 154篇 |
1978年 | 119篇 |
1977年 | 102篇 |
1976年 | 76篇 |
1975年 | 91篇 |
1974年 | 81篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Genetic diversity and molecular identification of mosquito species in the Anopheles maculatus group using the ITS2 region of rDNA. 总被引:2,自引:0,他引:2
C Walton P Somboon S M O'Loughlin S Zhang R E Harbach Y-M Linton B Chen K Nolan S Duong M-Y Fong I Vythilingum Z D Mohammed Ho Dinh Trung R K Butlin 《Infection, genetics and evolution》2007,7(1):93-102
The species diversity and genetic structure of mosquitoes belonging to the Anopheles maculatus group in Southeast Asia were investigated using the internal transcribed spacer 2 (ITS2) of ribosomal DNA (rDNA). A molecular phylogeny indicates the presence of at least one hitherto unrecognised species. Mosquitoes of chromosomal form K from eastern Thailand have a unique ITS2 sequence that is 3.7% divergent from the next most closely related taxon (An. sawadwongporni) in the group. In the context of negligible intraspecific variation at ITS2, this suggests that chromosomal form K is most probably a distinct species. Although An. maculatus sensu stricto from northern Thailand and southern Thailand/peninsular Malaysia differ from each other in chromosomal banding pattern and vectorial capacity, no intraspecific variation was observed in the ITS2 sequences of this species over this entire geographic area despite an extensive survey. A PCR-based identification method was developed to distinguish five species of the group (An. maculatus, An. dravidicus, An. pseudowillmori, An. sawadwongporni and chromosomal form K) to assist field-based studies in northwestern Thailand. Sequences from 187 mosquitoes (mostly An. maculatus and An. sawadwongporni) revealed no intraspecific variation in specimens from Thailand, Cambodia, mainland China, Malaysia, Taiwan and Vietnam, suggesting that this identification method will be widely applicable in Southeast Asia. The lack of detectable genetic structure also suggests that populations of these species are either connected by gene flow and/or share a recent common history. 相似文献
62.
Beth Hoskins Dudley F. Peeler Kathia Lawson Angie M. Barnes Ing K. Ho 《Brain research bulletin》1991,27(2):279-281
The effects of haloperidol on motor and functioning and cognitive functioning were studied in young (3-5 months old) and aged (20-22 months old) male mice by examining haloperidol-induced catalepsy and haloperidol-induced decrements in performance on a radial arm maze. The aged mice were much more sensitive to these adverse effects of haloperidol than were the young mice. Studies of the distribution of radioactivity from [3H]haloperidol to the brain indicated that the differences in sensitivity to this drug were not due to pharmacokinetic differences. The results demonstrate that mice are suitable for studies of aging-induced changes in the behavioral effects of neuroleptic agents. 相似文献
63.
YY Ho 《Journal of Medical Imaging and Radiation Oncology》2005,49(6):445-459
Bone and soft tissue tumours are rare neoplasms. There are five major roles of imaging in the management of primary musculoskeletal tumours, that is, to differentiate between benignity and malignancy, to evaluate for local tumour extension, to screen for metastases, to judge the effect of chemotherapy, and to monitor for recurrence. To accomplish this, multiple modalities are required because no single examination is able to complete all these tasks. These modalities include plain radiography, CT, MRI, conventional nuclear medicine as well as positron emission tomography (PET) imaging. Elsewhere, PET imaging has been discussed at length, because it is likely to be superior in the assessment of bone and soft tissue tumours over conventional nuclear medicine procedures. However, conventional nuclear medicine may be of value when PET is unavailable. In this review, an overview of anatomical imaging will be given and the role of non‐PET functional imaging will be discussed in detail. A variety of illustrative cases will be presented. 相似文献
64.
65.
E. W. Brien Joseph M. Mirra Steven Kessler M. Suen J. K. S. Ho W. T. Yang 《Skeletal radiology》1997,26(4):246-255
It is not uncommon for sarcomatous transformation of giant cell tumor (GCT) of bone to occur after radiation, but rarely
does malignant transformation occur spontaneously, with less than 15 cases reported up to 1995. Only four of these cases have
been documented in detail. We report two additional cases of GCT of bone spontaneously transforming or ”dedifferentiating”
into osteosarcoma without radiation therapy. The first case is absolutely unique and most interesting in that the dedifferentiation
process occurred in one of multiple GCT lung metastases 6 years after successful eradication of a primary tibial tumor. The
right lung was resected due to development of a large tumor, and at pathologic examination, demonstrated several small nodules
of conventional GCT and a much larger, 14-cm mass composed of a mixture of GCT and high-grade osteosarcoma. The second case
involved a physician, who had a large tumor in the sacrum with vague symptoms for 8 years. Open biopsy revealed conventional,
benign GCT of bone with a secondary aneurysmal bone cyst. Complete curettage 2 weeks later revealed, in addition to areas
of conventional, benign GCT a second component of very high grade osteosarcoma. Both patients died less than 1.5 years from
diagnosis. This report of osteosarcomatous transformation of a conventional GCT of bone strengthens the theory that there
is a mesenchymal cell line in GCT that may spontaneously tansform to sarcoma. 相似文献
66.
Martin Zeier Jolanta Perz Reinhold P Linke Ugo Donini Rüdiger Waldherr Konrad Andrassy Anthony D Ho Hartmut Goldschmidt 《Nephrology, dialysis, transplantation》2003,18(12):2644-2647
BACKGROUND: High-dose chemotherapy followed by autologous blood stem cell transplantation induces remission of plasma cell dyscrasia in patients with AL amyloidosis. The impact of this treatment on the glomerular amyloid mass is still unknown. METHODS: In the present study, the quantity of the renal amyloid mass before and more than 3 years after high-dose melphalan treatment and autologous blood stem cell transplantation was assessed in two patients. At the time of the second renal biopsy, both patients were in complete remission without detectable serum and urinary monoclonal IgA-lambda and a normal percentage of plasma cells in the bone marrow. RESULTS: In both patients with biopsy-proven AL amyloidosis, urinary protein excretion decreased from 7 g/24 h to <2 g/24 h more than 3 years after autologous blood stem cell transplantation. In contrast, glomerular amyloid deposits persisted, as shown in the second biopsy. CONCLUSION: Despite complete remission of the plasma cell dyscrasia and improvement of glomerular permeability, the amount of glomerular amyloid mass did not regress. 相似文献
67.
Amir Tejani Ping Leung Ho Lea Emmett Donald M Stablein 《American journal of transplantation》2002,2(2):142-147
Chronic rejection accounted for 32% of all graft losses in 7123 pediatric transplants. In a previous study acute, multiple acute and late acute rejections were risk factors for the development of chronic rejection. We postulated that the recent decrease in acute rejections would translate into a lower risk for chronic rejection among patients with recent transplants. We reviewed our data on patients transplanted from 1995 to 2000, and using multivariate analysis and a proportional hazards model developed risk factors for patients whose grafts had failed due to chronic rejection. A late initial rejection increased the risk of chronic rejection graft failure 3.6-fold (p < 0.001), while a second rejection resulted in further increase of 4.2-fold (p < 0.001). Recipients who received less than 5 mg/kg of cyclosporine at 30 days post-transplant had a relative risk (RR) of 1.9 (p = 0.02). Patients transplanted from 1995 to 2000 had a significantly lower risk (RR = 0.54, p < 0.001) of graft failure from chronic rejection than those who received their transplants earlier (1987-94). Since we were able to demonstrate that there is a decreased risk of chronic rejection graft failure in our study cohort, we would conclude that the goal of future transplants should be to minimize acute rejections. 相似文献
68.
69.
70.