全文获取类型
收费全文 | 14263篇 |
免费 | 933篇 |
国内免费 | 77篇 |
专业分类
耳鼻咽喉 | 122篇 |
儿科学 | 511篇 |
妇产科学 | 254篇 |
基础医学 | 1559篇 |
口腔科学 | 282篇 |
临床医学 | 1585篇 |
内科学 | 3376篇 |
皮肤病学 | 144篇 |
神经病学 | 1307篇 |
特种医学 | 672篇 |
外科学 | 2150篇 |
综合类 | 205篇 |
一般理论 | 3篇 |
预防医学 | 1051篇 |
眼科学 | 539篇 |
药学 | 731篇 |
中国医学 | 27篇 |
肿瘤学 | 755篇 |
出版年
2023年 | 102篇 |
2022年 | 99篇 |
2021年 | 178篇 |
2020年 | 199篇 |
2019年 | 204篇 |
2018年 | 286篇 |
2017年 | 209篇 |
2016年 | 245篇 |
2015年 | 279篇 |
2014年 | 417篇 |
2013年 | 568篇 |
2012年 | 675篇 |
2011年 | 824篇 |
2010年 | 505篇 |
2009年 | 503篇 |
2008年 | 753篇 |
2007年 | 850篇 |
2006年 | 850篇 |
2005年 | 792篇 |
2004年 | 809篇 |
2003年 | 788篇 |
2002年 | 670篇 |
2001年 | 142篇 |
2000年 | 108篇 |
1999年 | 134篇 |
1998年 | 225篇 |
1997年 | 230篇 |
1996年 | 191篇 |
1995年 | 187篇 |
1994年 | 148篇 |
1993年 | 146篇 |
1992年 | 137篇 |
1991年 | 98篇 |
1990年 | 94篇 |
1989年 | 122篇 |
1988年 | 104篇 |
1987年 | 117篇 |
1986年 | 107篇 |
1985年 | 107篇 |
1984年 | 136篇 |
1983年 | 124篇 |
1982年 | 147篇 |
1981年 | 129篇 |
1980年 | 139篇 |
1979年 | 64篇 |
1978年 | 74篇 |
1977年 | 86篇 |
1976年 | 71篇 |
1975年 | 51篇 |
1974年 | 58篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Mahmoud Elsawy Barry E. Storer Filippo Milano Brenda M. Sandmaier Colleen Delaney Rachel B. Salit Ahmed H. Rashad Ann E. Woolfrey Frederick R. Appelbaum Rainer Storb Mohamed L. Sorror 《Biology of blood and marrow transplantation》2019,25(5):1045-1052
The Hematopoietic Cell Transplantation-Specific Comorbidity Index (HCT-CI) was developed and validated to weigh the burden of pretransplantation comorbidities and estimate their impact on post-transplantation risks of nonrelapse mortality (NRM). Recently, the HCT-CI was augmented by the addition of both age and the values of 3 markers: ferritin, albumin, and platelet count. So far, research involving The HCT-CI has been limited almost exclusively to recipients of allogeneic hematopoietic cell transplantation (HCT) from HLA-matched grafts. To this end, we sought to investigate the discriminative capacity of an augmented comorbidity/age index among 724 recipients of allogeneic HCT from HLA-mismatched (n = 345), haploidentical (n = 117), and umbilical cord blood (UCB; n = 262) grafts between 2000 and 2013. In the overall cohort, the augmented comorbidity/age index had a higher c-statistic estimate for prediction of NRM compared with the original HCT-CI (.63 versus .59). Findings were similar for recipients of HLA-mismatched (.62 versus .59), haploidentical (.60 versus .54), or UCB grafts (.65 versus .61). Compared with patients with an HCT-CI score ≥4, those with a score <4 had a higher survival rate among recipients of HLA-mismatched (55% versus 39%; P < .0008), HLA-haploidentical (58% versus 38%; P = .01), or UCB (67% versus 48%; P = .004) grafts. Our results demonstrate the utility of the augmented comorbidity/age index as a valid prognostic tool among recipients of allogeneic HCT from alternative graft sources. 相似文献
2.
Identification of cultivable microorganisms from primary endodontic infections with exposed and unexposed pulp space 总被引:1,自引:0,他引:1
This study was aimed at comparing the cultivable microorganisms in canals with periapical radiolucencies with exposed and unexposed pulp space. Microbiological samples were taken and analyzed from 45 canals with exposed pulp space, and 43 canals with unexposed pulp space. The canal contents were analyzed by aerobic/anaerobic culture, and conventional identification techniques. There were 211 isolates of bacteria belonging to 28 genera and 55 species recovered from exposed canals. In the unexposed group, 185 isolates of bacteria were recovered, of which 54 species of 28 genera were identified. Among the four most common genera, Prevotella was significantly more common in the exposed group (51/211 in the exposed group versus 30/185 in the unexposed group) (p = 0.049), while there were no differences in prevalence of Actinomyces, Peptostreptococcus, and Campylobacter between two groups of canals. In addition, Fusobacterium nucleatum and Propionibacterium acne were significantly more common in the unexposed canals (p = 0.047 and p = 0.0051, respectively). Similarity in bacterial species in these two groups suggests that pulp space exposure may not be a significant factor in determining the type of bacteria present in infected canals. 相似文献
3.
Sharma AB Yonemura CY Curtis DA Finzen FC 《Journal of the California Dental Association》2008,36(4):269-273
The transition of patients from a dentate state to an implant-supported restoration requires significant planning. Traditionally, protocols have included the extraction of teeth and interim use of a removable prosthesis. Newer protocols include approaches to decrease the period of time a patient is required to use a traditional denture. The authors' purpose is to outline options and provide clinical examples when transitioning patients from natural dentition to an implant-supported prosthesis. 相似文献
4.
Tse ET Cheng LY Luk HW Chu FC Chai J Chow TW 《The International journal of prosthodontics》2006,19(4):371-372
This study aimed to compare the retentive forces of cast cobalt-chromium (Co-Cr) and commercially pure titanium (cpTi) clasps. A clasp assembly comprising a pair of symmetrical clasps was made to fit the opposite halves of a hardened stainless-steel sphere. This twin clasp was designed to counterbalance the tipping forces when the clasp assembly was drawn from the sphere. A total of 120 clasp assemblies were fabricated in cast Co-Cr and cpTi and placed at undercut depths of 0.25 mm, 0.50 mm, and 0.75 mm (n = 20 for each). For Co-Cr clasps, the retentive forces at these undercuts depths were 2.34 +/- 0.23 N, 4.65 +/- 0.35 N, and 7.56 +/- 0.50 N, respectively. The corresponding retentive forces for cpTi clasps were 1.24 +/- 0.13 N, 2.34 +/- 0.23 N, and 3.70 +/- 0.27 N. The retentive force of cpTi clasps was approximately half that of Co-Cr clasps for the same undercut depth. 相似文献
5.
In the healthy subgingiva, oral treponemes account for a small percentage of the total bacteria. However, in diseased periodontal pockets, treponemes thrive and become a dominant component of the bacterial population. Oral treponemes are uniquely adept at capitalizing on the environmental conditions that develop with periodontal disease. The molecular basis of adaptive responses of oral treponemes is just beginning to be investigated and defined. The completion of several treponeme genome sequences and the characterization of global regulatory systems provide an important starting point in the analysis of signaling and adaptive responses. In this review, we discuss existing literature focused on the genetic regulatory mechanisms of Treponema denticola and present an overview of the possible roles of regulatory proteins identified through genome analyses. This information provides insight into the possible molecular mechanisms utilized by oral spirochetes to survive in the periodontal pocket and transition from a minor to a dominant organism. 相似文献
6.
OBJECTIVES: The light absorption of dental photoinitiators should correlate with the spectral emission profiles of dental light curing units compared on an equivalent basis. Spectral data of dental photoinitiators and light curing units can be used to define the photon absorption efficiency (PAE) obtained by integrating the product of the absorption and emission spectra in terms of photons. This parameter can be used to identify the best performance for photochemical process with specific photoinitiators. METHODS: The efficiency of two LED and one QTH lamps were tested comparing their performances with the photoinitiators camphorquinone (CQ); phenylpropanedione (PPD); monoacylphosphine oxide (Lucirin TPO); and bisacylphosphine oxide (Irgacure 819). Absorption and emission spectra of the photoinitiators and the LED (Ultrablue I and Ultrablue IS) and QTH (Optilux 401) LCUs were determined in the 360-550nm range. RESULTS: CQ exhibited an absorption centered in the blue region and, although the maxima of PPD, MAPO, and BAPO were in the UV-A region, their absorption extended to the visible region. Power output maxima of the LCUs were at 467 (Ultrablue I), 454 (Ultrablue IS) and 493nm (Optilux 401), and the total power densities were 170+/-1, 470+/-4 and 444+/-4mW/cm(2), respectively. SIGNIFICANCE: The use of the PAE allows a prediction of the most efficient photoinitiator/LCU systems. For similar photoinitiator concentrations, Lucirin and CQ are most efficiently photoinitiated by the QTH unit, whereas the high-power LED device is more efficient for Irgacure. PPD is photoactivated similarly by both LCUs. 相似文献
7.
Lynne RE Liewehr FR West LA Patton WR Buxton TB McPherson JC 《Journal of endodontics》2003,29(3):187-190
The purpose of this study was to evaluate the antimicrobial activity of several medication preparations in root canal dentin infected with Enterococcus faecalis. Roots of extracted bovine incisors were prepared to standardized cylindrical test specimens, 5 mm in height. The smear layer was removed and the samples were autoclaved and then incubated at 37 degrees C/5% CO2 for 24 h in brain-heart infusion (BHI) broth containing 7.0 x 10(4) colony forming units per ml of E. faecalis. The samples were washed in phosphate buffered saline and mounted to individual culture wells with sticky wax. Test medications were applied to fill the canal lumina; medication groups were: (a) sterile H2O (positive control); (b) a 10% mixture of 1.0 g Ca(OH)2 USP in 10 ml sterile H2O; (c) 10% Ca(OH)2 in 0.12% chlorhexidine gluconate (Peridex); (d) Peridex; and (e) uninoculated BHI (negative control). The samples were incubated at 37 degrees C/5% CO2 for 24 h. Dentin samples for quantitative microbiology were then obtained with consecutive sterile burs (ISO 029, 035, 042). All three experimental groups demonstrated significantly greater antimicrobial activity than the positive control (p < 0.001). Group 2 demonstrated significantly greater antimicrobial activity than Group 3 or Group 4 at all dentin depths (p < 0.05). These results suggest that 10% Ca(OH)2 may be more effective than Peridex or 10% Ca(OH)2 in Peridex for the elimination of E. faecalis from dentin tubules. 相似文献
8.
Marie Therese Flores Barbro Malmgren Lars Andersson Jens Ove Andreasen Leif K. Bakland Frederick Barnett Cecilia Bourguignon Anthony DiAngelis Lamar Hicks Asgeir Sigurdsson Martin Trope Mitsuhiro Tsukiboshi Thomas von Arx 《Dental traumatology》2007,23(4):196-202
Abstract – Trauma to the primary dentition present special problems and the management is often different as compared with permanent teeth. An appropriate emergency treatment plan is important for a good prognosis. Guidelines are useful for delivering the best care possible in an efficient manner. The International Association of Dental Traumatology (IADT) has developed a consensus statement after a review of the dental literature and group discussions. Experienced researchers and clinicians from various specialties were included in the group. In cases in which the data did not appear conclusive, recommendations were based on the consensus opinion of the IADT board members. The guidelines represent the current best evidence based on literature research and professional opinion. In this third article out of three, the IADT Guidelines for the management of traumatic injuries in the primary dentition, are presented. 相似文献
9.
10.
Frederick C S Chu Wan K Wong Yiu K Wong Ben K C Chow Jason C F Cheng 《Quintessence international, dental digest》2003,34(9):670-673
Radiotherapy for the nasopharyngeal cancer patient with poor oral care may lead to severe deterioration of the dentition and may require multiple extractions. Although the use of an implant-retained overdenture can successfully restore the function and esthetics of edentulous patients, its use can be complicated by the tissue changes subsequent to head and neck irradiation. The difficulties in implant treatment planning for an edentulous patient with macroglossia and soft tissue changes following radiotherapy are discussed. 相似文献