全文获取类型
收费全文 | 11938篇 |
免费 | 1220篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 93篇 |
儿科学 | 242篇 |
妇产科学 | 293篇 |
基础医学 | 1503篇 |
口腔科学 | 174篇 |
临床医学 | 1815篇 |
内科学 | 2238篇 |
皮肤病学 | 159篇 |
神经病学 | 986篇 |
特种医学 | 510篇 |
外科学 | 1841篇 |
综合类 | 282篇 |
一般理论 | 19篇 |
预防医学 | 1399篇 |
眼科学 | 171篇 |
药学 | 892篇 |
1篇 | |
中国医学 | 13篇 |
肿瘤学 | 544篇 |
出版年
2023年 | 85篇 |
2022年 | 90篇 |
2021年 | 207篇 |
2020年 | 141篇 |
2019年 | 185篇 |
2018年 | 245篇 |
2017年 | 201篇 |
2016年 | 228篇 |
2015年 | 231篇 |
2014年 | 306篇 |
2013年 | 403篇 |
2012年 | 577篇 |
2011年 | 625篇 |
2010年 | 373篇 |
2009年 | 380篇 |
2008年 | 533篇 |
2007年 | 550篇 |
2006年 | 516篇 |
2005年 | 551篇 |
2004年 | 552篇 |
2003年 | 443篇 |
2002年 | 409篇 |
2001年 | 412篇 |
2000年 | 397篇 |
1999年 | 414篇 |
1998年 | 177篇 |
1997年 | 125篇 |
1996年 | 135篇 |
1995年 | 115篇 |
1994年 | 105篇 |
1993年 | 85篇 |
1992年 | 300篇 |
1991年 | 271篇 |
1990年 | 228篇 |
1989年 | 245篇 |
1988年 | 226篇 |
1987年 | 200篇 |
1986年 | 188篇 |
1985年 | 180篇 |
1984年 | 124篇 |
1983年 | 142篇 |
1982年 | 77篇 |
1981年 | 73篇 |
1979年 | 123篇 |
1977年 | 85篇 |
1975年 | 63篇 |
1974年 | 91篇 |
1973年 | 83篇 |
1972年 | 78篇 |
1971年 | 83篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
81.
Anderson RA; Evans LW; Irvine DS; McIntyre MA; Groome NP; Riley SC 《Human reproduction (Oxford, England)》1998,13(12):3319-3325
Follistatin is a binding protein for the activin and inhibin family of
hormones, regulating their biological activity. In the male reproductive
tract, the interaction of these factors is likely to be involved in the
regulation of the proliferation of several cell types. We have investigated
the presence of follistatin and activin A in seminal plasma using specific
immunoassays and have localized follistatin and activin/inhibin subunits in
the adult human testis, prostate and seminal vesicle to establish their
likely sources. High concentrations of immunoreactive follistatin were
present in seminal plasma in normal men (mean 97.9 ng/ml; 1.43 ng/ml in
peripheral plasma) and were similar in men with oligo/azoospermia and
following vasectomy. Follistatin immunoreactivity was localized to both
Leydig and Sertoli cells of the testis, and to epithelial cells of the
prostate gland and seminal vesicle, which are likely to be the predominant
sources of the hormone in seminal plasma. Activin A was also present in
seminal plasma in normal men but was undetectable following vasectomy, thus
deriving from the testis. Consistent with this finding, the betaA-subunit
was immunolocalized in Sertoli and Leydig cells but was not present in
seminal vesicle or prostate gland. The functional significance of the high
concentrations of follistatin secreted into seminal plasma by the prostate
gland and/or seminal vesicle is uncertain, but they may regulate the
biological activity of testis-derived activin A and inhibin B.
相似文献
82.
83.
Dimitrios A. Panussis Mark W. Cook Lisa L. Rifkin Jacqueline E. Snider Joseph T. Strong Rebecca M. McGrane Richard K. Wilson Elaine R. Mardis 《Genome research》1998,8(5):543-548
This work describes the design and construction of a device that facilitates the loading of DNA samples onto polyacrylamide gels for detection in the Perkin Elmer/Applied Biosystems (PE/ABI) 373 and 377 DNA sequencing instruments. The device is mounted onto the existing gel cassettes and makes the process of loading high-density gels less cumbersome while the associated time and errors are reduced. The principle of operation includes the simultaneous transfer of the entire batch of samples, in which a spring-loaded air cylinder generates positive pressure and flexible silica capillaries transfer the samples. A retractable capillary array carrier allows the delivery ends of the capillaries to be held up clear of the gel during loader attachment on the gel plates, while enabling their insertion in the gel wells once the device is securely mounted. Gel-loading devices capable of simultaneously transferring 72 samples onto the PE/ABI 373 and 377 are currently being used in our production sequencing groups while a 96-sample transfer prototype undergoes testing. 相似文献
84.
Multiple sclerosis is a demyelinating disease of the central nervous system with genetic, viral and autoimmune characteristics. Myelin basic protein (MBP) is a suspected target autoantigen since it induces experimental autoimmune encephalomyelitis, an animal model closely resembling multiple sclerosis. The disease is mediated by Class II restricted, MBP-reactive T cells possessing the T helper/inducer phenotype. In the present study, we have isolated MBP-reactive T cell clones from the peripheral blood of a chronic progressive multiple sclerosis patient. The clones displayed blastogenic memory responses when rechallenged with the autoantigen and irradiated autologous lymphocytes. MBP recognition by the autoantigen-reactive T lymphocytes was restricted by major histocompatibility complex Class II antigens. Both CD4+8- and CD4-8+ MBP-reactive T cell clones were obtained. 相似文献
85.
Non-linkage of the islet amyloid polypeptide gene with Type 2 (non-insulin-dependent) diabetes mellitus 总被引:1,自引:1,他引:0
J. T. E. Cook P. P. Patel A. Clark J. W. M. Höppener C. J. M. Lips S. Mosselman S. O'Rahilly R. C. Page J. S. Wainscoat R. C. Turner 《Diabetologia》1991,34(2):103-108
Summary Type 2 (non-insulin-dependent) diabetes is associated with the deposition of islet amyloid. The major formative peptide, islet amyloid polypeptide, has recently been characterised and an abnormality of the structure or expression of this gene is a possible candidate for the inherited component of Type 2 diabetes. A restriction fragment length polymorphism of the gene has been identified with Pvu II. To study the relationship between the islet amyloid polypeptide gene and Type 2 diabetes, two distinct genetic approaches have been undertaken. Firstly, non-linkage has been demonstrated in four pedigrees, with four normoglycaemic first degree relatives having an allele associated with diabetes in other family members, and one affected relative not having the putatively associated allele. The LOD score taking age-related penetrance into account was –1.68, making linkage unlikely (p=0.02). Secondly, in a population-based restriction fragment length polymorphism survey, no linkage disequilibrium of the alleles was found between a population of unrelated Caucasian subjects with Type 2 diabetes and a normal population. A mutation in or near the islet amyloid polypeptide gene is thus unlikely to be a common cause of Type 2 diabetes. 相似文献
86.
87.
M D Murphey J L Quale N L Martin J M Bramble L T Cook S J Dwyer 《AJR. American journal of roentgenology》1992,158(1):19-27
Computed radiography is a 2K x 2K x 10 bit digital radiographic system that replaces the film-screen combination with a photo-stimulable phosphor plate. The advantages of this relatively new technology include linear detector response, improved detector efficiency, and digital processing capabilities. Musculoskeletal applications benefit significantly from these attributes, which result clinically in the ability to reduce both radiation dose and number of exposures. Studies of observers' performance have shown no statistically significant difference in diagnostic accuracy between film-screen and computed radiographic musculoskeletal images. Computed radiography is particularly useful in the evaluation of the musculoskeletal system in traumatized patients with portable radiographs, spine radiographs, scoliosis studies, and depiction of soft-tissue abnormalities. Limitations include change in image format and size, high cost, decreased spatial resolution, restricted throughput, increased perception of noise, and new artifacts that must be recognized. Spatial resolution limitations of computed radiography in identification of fine detail information can be improved by using magnification techniques. Radiation dose reduction with an exposure decrease of 25-50% can be achieved without loss of diagnostic accuracy, although this depends on the examination and the abnormality. An interactive workstation is important in the use of a computed radiographic system with capabilities to adjust display parameters to best depict images and disease. We conclude that computed radiography is an alternative to film-screen radiography without significant differences in diagnostic quality in the evaluation of musculoskeletal images. 相似文献
88.
89.
Multiply Recurrent Trichilemmal Carcinoma With Perineural Invasion and Cytokeratin 17 Positivity 总被引:4,自引:0,他引:4
Julie E. Allee MD George Cotsarelis MD Benjamin Solky MD Jonathan L. Cook MD 《Dermatologic surgery》2003,29(8):886-889
BACKGROUND: Trichilemmal carcinoma is an uncommon cutaneous malignancy that is thought to be the malignant counterpart of the trichilemmoma. Despite histologic features such as pronounced cytologic atypia, trichilemmal carcinoma is often described as having a rather benign clinical course. Cases of tumor recurrence after therapy are uncommon, and tumor neurotropism has never been described. OBJECTIVE: A case of multiply recurrent trichilemmal carcinoma with perineural invasion is described. The outer root sheath differentiation of this neoplasm is confirmed with the use of novel antibodies directed toward cytokeratins that are expressed in this area of the hair follicle. METHODS: The trichilemmal carcinoma was excised using the Mohs surgical technique. Tissue obtained during the extirpation of the tumor was subjected to immunohistochemical staining for cytokeratin 15, cytokeratin 17, and c-erb-B2. RESULTS: Tumor neurotropism was noted. The trichilemmal carcinoma demonstrated abundant cytoplasmic staining for cytokeratin 17 and c-erb-B2. CONCLUSIONS: In distinction to previous reports, this case reveals that trichilemmal carcinoma can demonstrate significant biological aggression, as reflected by tumor neurotropism and by failure to respond to multiple surgical excisions. The purported outer root sheath differentiation of this neoplasm is confirmed with the use of novel immunohistochemical staining. This immunohistochemical staining may be useful in differentiating trichilemmal carcinoma from other clear cell neoplasms. 相似文献
90.
Vaida S. J.; Gaitini L. A.; Cook T. M.; Awan R.; Nolan J. P. 《British journal of anaesthesia》2004,92(6):905
EditorWe read with interest the case report by Awan andcolleagues,1 describing successful use of the ProSealTM laryngealmask airway (PLMA) after failed tracheal intubation in a parturientundergoing Caesarean section. After securing the airway withthe PLMA, the authors removed it and tried again to performtracheal intubation. We think that the PLMA can be left in placeand used as a definitive airway after failed intubation in Caesareansection. We report another case where the PLMA 相似文献