全文获取类型
收费全文 | 17799篇 |
免费 | 1392篇 |
国内免费 | 57篇 |
专业分类
耳鼻咽喉 | 196篇 |
儿科学 | 464篇 |
妇产科学 | 282篇 |
基础医学 | 2231篇 |
口腔科学 | 245篇 |
临床医学 | 1893篇 |
内科学 | 4232篇 |
皮肤病学 | 289篇 |
神经病学 | 1552篇 |
特种医学 | 585篇 |
外科学 | 3261篇 |
综合类 | 212篇 |
一般理论 | 16篇 |
预防医学 | 1359篇 |
眼科学 | 345篇 |
药学 | 1000篇 |
中国医学 | 41篇 |
肿瘤学 | 1045篇 |
出版年
2023年 | 179篇 |
2022年 | 377篇 |
2021年 | 888篇 |
2020年 | 459篇 |
2019年 | 714篇 |
2018年 | 805篇 |
2017年 | 551篇 |
2016年 | 550篇 |
2015年 | 639篇 |
2014年 | 896篇 |
2013年 | 1007篇 |
2012年 | 1540篇 |
2011年 | 1520篇 |
2010年 | 800篇 |
2009年 | 663篇 |
2008年 | 1088篇 |
2007年 | 1035篇 |
2006年 | 918篇 |
2005年 | 808篇 |
2004年 | 700篇 |
2003年 | 618篇 |
2002年 | 486篇 |
2001年 | 157篇 |
2000年 | 173篇 |
1999年 | 152篇 |
1998年 | 90篇 |
1997年 | 66篇 |
1996年 | 58篇 |
1995年 | 46篇 |
1994年 | 37篇 |
1993年 | 57篇 |
1992年 | 100篇 |
1991年 | 82篇 |
1990年 | 79篇 |
1989年 | 80篇 |
1988年 | 70篇 |
1987年 | 76篇 |
1986年 | 56篇 |
1985年 | 69篇 |
1984年 | 51篇 |
1983年 | 56篇 |
1982年 | 41篇 |
1981年 | 42篇 |
1980年 | 32篇 |
1979年 | 50篇 |
1978年 | 37篇 |
1976年 | 37篇 |
1974年 | 27篇 |
1973年 | 19篇 |
1971年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Barbara Stanley Beth Brodsky Joshua D Nelson Rebecca Dulit 《Archives of Suicide Research》2007,11(4):337-341
The purpose of this study is to evaluate the effectiveness of a shorter course of Dialectical Behavior Therapy (DBT) in enhancing treatment retention and reducing: urges to engage in non-suicidal self injury (NSSI), NSSI, suicide ideation, and subjective distress in borderline personality disorder (BPD). Twenty patients with BPD received a six-month course of Dialectical Behavior Therapy (DBT-B). DBT-B was delivered in the standard manner except for the shortened duration from one-year minimum to six months. All variables were measured at baseline, and at six months. Data were analyzed using paired t-tests. Treatment retention rate was 95%. Significant reductions were found in NSSI urges, NSSI, suicide ideation, subjective distress, depression, and hopelessness between baseline and six months. These results support the use of DBT-B in a six-month format when NSSI and suicidal behavior and ideation are the targeted behaviors. Target behaviors were reduced significantly and retention was extremely high in comparison to other interventions for this population. A large scale randomized controlled trial investigating its efficacy is warranted to determine if the results can be replicated and if improvement can be sustained. 相似文献
53.
The Role of Donor Bone Marrow Infusions in Withdrawal of Immunosuppression in Adult Liver Allotransplantation 总被引:3,自引:0,他引:3
Panagiotis Tryphonopoulos reas G. Tzakis Debbie Weppler Rolando Garcia-Morales Tomoaki Kato Juan R. Madariaga David M. Levi Seigo Nishida Jang Moon Gennaro Selvaggi Arie Regev Caio Nery Pablo Bejarano Amr Khaled Gary Kleiner Violet Esquenazi Joshua Miller Philip Ruiz Camillo Ricordi 《American journal of transplantation》2005,5(3):608-613
We investigated the role of donor bone marrow cell (DBMC) infusions in immunosuppression withdrawal in adult liver transplantation. Patients enrolled were at least 3 years post-transplantation, with stable graft function. Forty-five (study group: G1) received DBMC, and 59 (control group: G2) did not. Immunosuppression was reduced by one third upon enrollment, by another third the second year of the study and was completely withdrawn the third year. Patient and graft survival were similar between the two groups. Although rejection episodes were significantly less in G1 the first 2 years of the study (35% vs. 57%, p = 0.016), there was no significant difference overall (74% vs. 81%, p = 0.14). Until February 2004, 20 patients, 10 in each group, were immunosuppression free for 1-3 years. Approximately 20% of long-term survivors of liver transplantation can successfully discontinue their immunosuppression. DBMC infusions, do not increase this likelihood. 相似文献
54.
Jeffrey S. Cohen M.D. I. Benjamin Paz M.D. Margaret R. O'Donnell M.D. Dr. Joshua D. I. Ellenhorn M.D. 《Diseases of the colon and rectum》1996,39(9):981-985
PURPOSE: Bone marrow transplantation (BMT) is often associated with profound neutropenia. Allogeneic transplant recipients also have defects in both humoral and cellular immunity and thus are subject to increased risk of serious, often life-threatening, infection even beyond the period of granulocyte recovery. The current study was undertaken to evaluate patients who required operative intervention for perianal sepsis following BMT. METHODS: The bone marrow transplant database at a single institution was used to identify all patients diagnosed with perianal infections after autologous or allogeneic BMT. Charts were reviewed in a retrospective manner. RESULTS: Over a ten-year period ending in November 1993, 963 BMT were performed at the City of Hope National Medical Center. Twenty-four patients were diagnosed with perianal infections foEowing their transplants. Fifteen patients did not have purulent collections requiring drainage and were treated with antibiotics and supportive measures alone. Nine patients (37.5 percent) required surgical intervention between 10 and 380 days following transplantation. At the time of surgical intervention, seven patients had purulent collections and two patients had acute and chronic inflammation, tissue necrosis, and fibrosis. Of the two patients with an absolute neutrophil count less than 1,000, a purulent collection was found in one of the patients. Cultures taken from perianal abscesses were almost all polymicrobial, and the most common organisms were
Escherichia coli, Bacteroides, Enterococcus,and
Klebsiella.For those patients undergoing surgical intervention, mean time to complete wound closure by secondary intention was 37.6 days; five patients healed in less than 15 days, two patients healed at 93 and 114 days, and two patients had persistent, open wounds at time of death, which was unrelated to their perianal disease. Five patients were receiving systemic steroids at time of surgical intervention; this did not appear to affect time to wound healing. CONCLUSIONS: Perianal infections are a rare complication of BMT. Majority of these infections are polymicrobial, and organisms isolated are similar to those seen in the perianal infections of nonimmunosuppressed patients. Despite steroid use, granulocytopenia does not exclude the possible presence of purulent collections, and clinical examination should guide the decision for surgical drainage. In general, perianal wound healing is not prolonged in BMT patients.Poster presentation at the meeting of The American Society of Colon and Rectal Surgeons, Montreal, Quebec, Canada, May 7 to 12, 1995. 相似文献
55.
56.
SARS associated coronavirus has a recombinant polymerase and coronaviruses have a history of host-shifting. 总被引:3,自引:0,他引:3
The sudden appearance and potential lethality of severe acute respiratory syndrome associated coronavirus (SARS-CoV) in humans has focused attention on understanding its origins. Here, we assess phylogenetic relationships for the SARS-CoV lineage as well as the history of host-species shifts for SARS-CoV and other coronaviruses. We used a Bayesian phylogenetic inference approach with sliding window analyses of three SARS-CoV proteins: RNA dependent RNA polymerase (RDRP), nucleocapsid (N) and spike (S). Conservation of RDRP allowed us to use a set of Arteriviridae taxa to root the Coronaviridae phylogeny. We found strong evidence for a recombination breakpoint within SARS-CoV RDRP, based on different, well supported trees for a 5' fragment (supporting SARS-CoV as sister to a clade including all other coronaviruses) and a 3' fragment (supporting SARS-CoV as sister to group three avian coronaviruses). These different topologies are statistically significant: the optimal 5' tree could be rejected for the 3' region, and the optimal 3' tree could be rejected for the 5' region. We did not find statistical evidence for recombination in analyses of N and S, as there is little signal to differentiate among alternative trees. Comparison of phylogenetic trees for 11 known host-species and 36 coronaviruses, representing coronavirus groups 1-3 and SARS-CoV, based on N showed statistical incongruence indicating multiple host-species shifts for coronaviruses. Inference of host-species associations is highly sensitive to sampling and must be considered cautiously. However, current sampling suggests host-species shifts between mouse and rat, chicken and turkey, mammals and manx shearwater, and humans and other mammals. The sister relationship between avian coronaviruses and the 3' RDRP fragment of SARS-CoV suggests an additional host-species shift. Demonstration of recombination in the SARS-CoV lineage indicates its potential for rapid unpredictable change, a potentially important challenge for public health management and for drug and vaccine development. 相似文献
57.
Prognostic factors in myeloma are not only important for allowing comparisons to be made between therapeutic protocols but they also provide us with an insight into the pathophysiology of the disease and important mechanisms which result in disease progression. Prognostic factors in myeloma relate to the inherent proliferative capacity of the malignant clone, tumor bulk, renal function and other factors which reflect tumor host and host tumor interactions. The highly significant effect of the labelling index (LI) suggests that the clonogenic cell is ontologically very close to the malignant plasma cell on which the labelling index is derived. The explanation for the important role of the β2-microglobulin (β2M) level over and above its reflection of renal function is as yet unclear. 相似文献
58.
Flickering fusion pores comparable with initial exocytotic pores occur in protein-free phospholipid bilayers
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Alexandr Chanturiya Leonid V. Chernomordik Joshua Zimmerberg 《Proceedings of the National Academy of Sciences of the United States of America》1997,94(26):14423-14428
For the act of membrane fusion, there are two competing, mutually exclusive molecular models that differ in the structure of the initial pore, the pathway for ionic continuity between formerly separated volumes. Because biological “fusion pores” can be as small as ionic channels or gap junctions, one model posits a proteinaceous initial fusion pore. Because biological fusion pore conductance varies widely, another model proposes a lipidic initial pore. We have found pore opening and flickering during the fusion of protein-free phospholipid vesicles with planar phospholipid bilayers. Fusion pore formation appears to follow the coalescence of contacting monolayers to create a zone of hemifusion where continuity between the two adherent membranes is lipidic, but not aqueous. Hypotonic stress, causing tension in the vesicle membrane, promotes complete fusion. Pores closed soon after opening (flickering), and the distribution of fusion pore conductance appears similar to the distribution of initial fusion pores in biological fusion. Because small flickering pores can form in the absence of protein, the existence of small pores in biological fusion cannot be an argument in support of models based on proteinaceous pores. Rather, these results support the model of a lipidic fusion pore developing within a hemifused contact site. 相似文献
59.
60.
Use of Internet information by women with breast cancer 总被引:1,自引:0,他引:1